Coatings & Surface Treatments
A complete guide to metal coatings and surface engineering: anodizing, PVD, CVD, electroplating, thermal spray, powder coating, conversion coatings, hard facing, and surface finishing — with corrosion resistance, hardness, and application comparisons across 16 categories.
🎨Coatings — Surface Treatments & Coatings
Coating — changing surface properties: corrosion · wear · friction · aesthetics · conductivity · heat. The right coating depends on the material, environment, budget, and standard.
Video course · METAL HUB
Coatings, Finishes & Paint
An animated course on everything that happens to a part after machining: from surface preparation, through conversion coatings, metallic coatings and paint, to thermal spray, PVD and testing. Each chapter explains how the process works, what it gives you, how to design a part for it, what goes wrong, and what drives the cost.
21 chaptersAbout 2 hours of viewing6 coating familiesEnglish narration and subtitles
Every chapter follows the same order
- How it worksThe principle and the process, animated.
- Numbers and standardsThicknesses, temperatures, and classes per the standard.
- Part designWhat to put on the drawing, and how to avoid trouble.
- Common problemsWhat goes wrong, and why.
- What drives the costWhat really sets the price.
Who the course is for
- Production and finishing staffUnderstand what happens to the part, and why preparation matters so much
- Engineers and designersChoose the right coating and specify it on the drawing
- Purchasing, cost estimating and qualityUnderstand requirements, standards, testing and cost drivers
All chapters
Anodizing Type II — Sulfuric (Common)
MIL-A-86257-25μmColored
StandardMIL-A-8625 Type II / ISO 7599
Thickness7-25 μm
HardnessHV 200-300
BathH2SO4 15-20% · 18-22°C · 12-18V
ColorsBlack · Red · Blue · Gold · Green · Pink
SealingDI Water 96°C / Ni-Acetate / PTFE
Type II = most common. Sealing mandatory: closes pores.
✓ Vivid colors. ↑corrosion resistance. Aesthetics
✓ Electrically conductive after Chromic Seal
✗ 2024-T3 = problem (high Cu)
✗ Ra ↑20-30% in the layer
▶ YouTube✓ Vivid colors. ↑corrosion resistance. Aesthetics
✓ Electrically conductive after Chromic Seal
✗ 2024-T3 = problem (high Cu)
✗ Ra ↑20-30% in the layer
Anodizing Type III — Hard Anodize
MIL-A-8625 III25-100μmHV 400-600
StandardMIL-A-8625 Type III / AMS 2469
Thickness25-100 μm
HardnessHV 400-600
Bath Temp.-5 to 0°C · ↑current
ColorBlack/dark grey only
Useair cylinders, pistons, aerospace
50% layer grows inward, 50% outward.
✓ Maximum hardness for Al · wear resistance
✓ 25μm layer = +12.5μm per side
✗ One color only · expensive · high Ra
▶ YouTube✓ Maximum hardness for Al · wear resistance
✓ 25μm layer = +12.5μm per side
✗ One color only · expensive · high Ra
Anodizing Type I — Chromic
MIL-A-8625 I0.5-2.5μmCr(VI)
StandardMIL-A-8625 Type I/IB
Thickness0.5-2.5 μm
Advantagedoesn't change dimensions!
AlternativeType IB (LHC) — eco-friendly
✓ Minimal dimensional change — perfect for precision
✓ Excellent aerospace protection
✗ CrO3 = Cr(VI) carcinogenic! REACH/RoHS
▶ YouTube✓ Excellent aerospace protection
✗ CrO3 = Cr(VI) carcinogenic! REACH/RoHS
TSA — Tartaric-Sulfuric Anodize
RoHSAirbusType I Substitute
Developed byAirbus/EADS — RoHS substitute for Type I
Thickness2-4 μm
UseAirbus A350/A380 · Boeing 787
✓ RoHS / REACH — no Cr(VI)
✓ Corrosion resistance = Type I
✓ Excellent primer adhesion
▶ YouTube✓ Corrosion resistance = Type I
✓ Excellent primer adhesion
| Type | Standard | Thickness μm | HV | Advantage | Disadvantage |
|---|---|---|---|---|---|
| Type II | MIL-A-8625 II | 7-25 | 200-300 | colors, common | Ra ↑20% |
| Type III | MIL-A-8625 III | 25-100 | 400-600 | maximum wear | expensive, high Ra |
| Type I | MIL-A-8625 I | 0.5-2.5 | 200-250 | ↓dimensions | Cr(VI) carcinogenic |
| TSA | Airbus Spec | 2-4 | 200-250 | RoHS | less common |
TiN — Titanium Nitride PVD
GoldHV 23002-5μm
MethodCathodic Arc / Magnetron Sputtering
Thickness2-5 μm
HardnessHV 2300
Tmax500°C
Usebasic cutting tools, drills
Colorpolished gold
The most common PVD coating.
✓ Cheap and common. ↑tool life x2-4
✗ Low Tmax — not for SS/Ti dry cutting
▶ YouTube✓ Cheap and common. ↑tool life x2-4
✗ Low Tmax — not for SS/Ti dry cutting
TiAlN — Ti-Al Nitride PVD
HV 3300Tmax 800°CDry Cutting
Thickness2-5 μm
HardnessHV 2300-3500
Tmax800°C
Usefast dry milling, SS, Inconel, Ti
Colordark grey / greenish
Al2O3 forms on the layer under heat — protective!
✓ Fast dry cutting of Inconel/Ti
✓ ↑tool life x4-8 vs TiN
✗ Hard to see wear (dark color)
▶ YouTube✓ Fast dry cutting of Inconel/Ti
✓ ↑tool life x4-8 vs TiN
✗ Hard to see wear (dark color)
AlCrN — Al-Cr Nitride PVD
HV 3200Tmax 1100°CSteel HRC60+
Thickness2-5 μm
HardnessHV 3000-3200
Tmax1100°C
Useheavy milling, Inconel, Steel HRC 60+
ManufacturersOerlikon Balzers BALINIT
Cr replaces part of Ti = ↑Tmax + ↑oxidation resistance
✓ Best for Steel HRC 60+
✗ More expensive than TiAlN
▶ YouTube✓ Best for Steel HRC 60+
✗ More expensive than TiAlN
CrN — Chromium Nitride PVD
HV 1800Decorative ChromeEco-Friendly
Thickness5-20 μm
HardnessHV 1800
Tmax700°C
UseDecorative Chrome, molds, valves
✓ Bright Chrome without Cr(VI)!
✓ Anti-Stick for plastic molds
✗ Less hard than TiAlN/AlCrN
▶ YouTube✓ Anti-Stick for plastic molds
✗ Less hard than TiAlN/AlCrN
DLC — Diamond-Like Carbon
HV 3000-5000μ=0.08PACVD
Thickness0.5-4 μm
HardnessHV 3000-5000
Frictionμ=0.05-0.15 (a-C:H) / μ=0.03-0.10 (dry ta-C) — lowest!
Tmax300°C (limited!)
UseAl, engines, medical, luxury watches
a-C:H (Hydrogenated) / ta-C (Tetrahedral)
✓ ↓maximum friction reduction. Excellent for Al
✓ FDA-approved bio-cells
✗ Tmax only 300°C!
▶ YouTube✓ ↓maximum friction reduction. Excellent for Al
✓ FDA-approved bio-cells
✗ Tmax only 300°C!
Nano-Composite TiAlSiN / AlCrSiN
HV 4000+Tmax 1200°CNext-Gen
Thickness2-4 μm
HardnessHV 3500-4500
Tmax1100-1200°C
UseHardened Steel, Ti, CFRP, maximum speed
Nano Si3N4 Amorphous matrix = blocks crack propagation
✓ ↑↑tool life. Next-gen PVD
✗ Expensive. Requires advanced equipment
▶ YouTube✓ ↑↑tool life. Next-gen PVD
✗ Expensive. Requires advanced equipment
| Coating | HV | Tmax°C | μ | Use | Cost |
|---|---|---|---|---|---|
| TiN | 2300 | 500 | 0.4 | general milling | ⭐⭐ |
| TiAlN | 2300-3500 | 800 | 0.4 | SS, Inconel | ⭐⭐⭐ |
| AlCrN | 3000-3200 | 1100 | 0.35 | HRC 60+ | ⭐⭐⭐⭐ |
| CrN | 1800 | 700 | 0.3 | Decorative, molds | ⭐⭐⭐ |
| DLC | 3000-5000 | 300 | 0.08 | Al, medical | ⭐⭐⭐⭐ |
| Nano TiAlSiN | 3500-4500 | 1200 | 0.3 | maximum speed | ⭐⭐⭐⭐⭐ |
CVD — Chemical Vapor Deposition
TiC/TiN/Al2O3Multi-layer5-20μm
ProcessTiCl4 + CH4/N2 = TiC/TiN @ 900-1050°C
Thickness5-20 μm
StructureTiN/TiC/Al2O3/TiN Multi-layer
Usecarbide inserts, heavy cutting
Each layer has a role: TiN (base) = TiC (wear) = Al2O3 (heat) = TiN (ID)
✓ ↑insert life for continuous cutting
✗ high temp. = residual stresses
▶ YouTube✓ ↑insert life for continuous cutting
✗ high temp. = residual stresses
Diamond CVD — PCD on Substrate
HV 10000CFRP↓absolute wear
Thickness10-100 μm
HardnessHV 8000-10000
UseCFRP, Al-Si, ceramics, graphite
MethodHFCVD / MPCVD
✓ ↑↑↑CFRP tool life x100
✗ Not for steel! Fe + C = graphite = wear
▶ YouTube✗ Not for steel! Fe + C = graphite = wear
MT-CVD — Medium Temperature
700-850°CTiCN
Temp.700-850°C (vs 1050°C standard)
Layerthick TiCN + Al2O3
✓ ↓thermal distortion. ↑insert life
✓ Combining MT-CVD + PVD = ↑↑performance
▶ YouTube✓ Combining MT-CVD + PVD = ↑↑performance
Hard Chrome
HV 900-1100Cr(VI)!AMS 2406
StandardAMS 2406 /
Thickness12-500 μm
HardnessHV 900-1100
Useshafts, pistons, roll grinding wheels
IssueCr(VI) carcinogenic! REACH restrictions
Hard Chrome = standard for shaft and piston rebuild.
Crack network = ↑oil retention but ↓corrosion resistance
✓ Excellent dimensional restoration
✗ Cr(VI) — carcinogenic! EPA
✗ Being replaced by HVOF/EN
▶ YouTubeCrack network = ↑oil retention but ↓corrosion resistance
✓ Excellent dimensional restoration
✗ Cr(VI) — carcinogenic! EPA
✗ Being replaced by HVOF/EN
Zinc Plating
SacrificialSalt Spray 200hCheap
Thickness5-25 μm
ChromateYellow/Blue/Black Passivate after
StandardASTM B633 · ISO 4042
Usebolts, nuts, car body sheet metal
Sacrificial Anode: Zn is consumed instead of the steel!
Yellow Chromate = Cr(III) today (RoHS)
✓ Cheapest for corrosion protection
✗ Not for HCP! (Hydrogen Embrittlement RM>1000)
▶ YouTubeYellow Chromate = Cr(III) today (RoHS)
✓ Cheapest for corrosion protection
✗ Not for HCP! (Hydrogen Embrittlement RM>1000)
Electroless Nickel — EN
MIL-C-26074Perfectly UniformHV 1000
StandardMIL-C-26074 / AMS 2404
Thickness5-125 μm
HardnessHV 500 (as-plated) = HV 1000 (after 400°C!)
P%Low-P: 2-5% / High-P: 10-13% (↑corrosion resistance)
Usecomputer boards, firearms, valves
Auto-Catalytic — no current needed! Perfectly uniform.
High-P = Amorphous = non-magnetic + ↑corrosion resistance
✓ Hard Chrome substitute without Cr(VI), without HE
✓ Annealing 400°C = HV 1100
▶ YouTubeHigh-P = Amorphous = non-magnetic + ↑corrosion resistance
✓ Hard Chrome substitute without Cr(VI), without HE
✓ Annealing 400°C = HV 1100
Nickel Electroplating
HV 150-500EMI
TypesBright Ni (HV500, aesthetic) / Sulfamate (HV150, ↓stress)
UseEMI Shielding, precision interfaces, base for Cr/Au
Sulfamate = ↓Internal Stress = for delicate parts
✓ Base layer for Chrome, Gold, Silver
✗ Ni is allergenic! Not for skin-contact products
▶ YouTube✓ Base layer for Chrome, Gold, Silver
✗ Ni is allergenic! Not for skin-contact products
Flash Gold / Au Immersion — Thin Au
0.025-0.1μmENIGRoHS
Thickness0.025-0.1 μm — Flash only
MethodImmersion (ENIG) / Strike Gold
Purposepreventing Tarnish on Ni/Cu. Solderable.
StandardIPC-4552 (ENIG) / IPC-4556 (ENEPIG)
UsePCB Surface Finish, Au strike before plating
Costcheap — minimal Au quantity
Flash = thin Au layer for protection only — not for friction!
ENIG: EN 3-5μm + Au 0.05-0.1μm = the PCB standard
✓ Solderable + Oxidation-free + RoHS
✓ ↓cost. Protection for electrical contact
✗ Au Flash = not for Wire Bonding (too thin)
✗ ENIG: Black Pad! Ni corrosion = contact failure
▶ YouTubeENIG: EN 3-5μm + Au 0.05-0.1μm = the PCB standard
✓ Solderable + Oxidation-free + RoHS
✓ ↓cost. Protection for electrical contact
✗ Au Flash = not for Wire Bonding (too thin)
✗ ENIG: Black Pad! Ni corrosion = contact failure
Soft Gold — Au99.9% for Wire Bonding
99.9% AuWire BondSoft HV60
Thickness0.5-5 μm (Wire Bond: 0.5-1μm)
Purity99.9%+ Au — pure!
HardnessHV 60-90 (soft = ductile!)
BathCyanide Bath (Au-KCN) / Non-Cyanide
UseWire Bonding IC, Semiconductor Packages, Lead Frame
StandardMIL-G-45204 Type III
Soft Gold = grain structure suited to Wire Bonding (Al/Au wire)
Purity mandatory: Cu/Fe contamination = Wire Bond failure
✓ Wire Bondable! Au-Au and Al-Au thermosonic bonding
✓ No Tarnish. No corrosion, ever
✗ Soft = ↓wear resistance in contacts
✗ Expensive: Au=$60/g. Bath monitored strictly
▶ YouTubePurity mandatory: Cu/Fe contamination = Wire Bond failure
✓ Wire Bondable! Au-Au and Al-Au thermosonic bonding
✓ No Tarnish. No corrosion, ever
✗ Soft = ↓wear resistance in contacts
✗ Expensive: Au=$60/g. Bath monitored strictly
Hard Gold — AuCo / AuNi for Contacts
HV 130-200Wear ResistContacts
Thickness0.5-5 μm
CompositionAu + 0.1-0.3% Co / Au + 0.1% Ni
HardnessHV 130-200 (vs Soft Au: HV 60)
Insertion Cycles50,000-100,000+ (connectors)
Useelectronic connectors, buttons, socket contacts
StandardMIL-G-45204 Type I/II / ASTM B488
AuCo = most common for hard contacts. Co = ↑hardness + ↑wear resistance
AuNi = alternative (Ni-free option = AuCo)
✓ ↑↑wear resistance vs Soft Gold
✓ 50K+ insertion/extraction cycles
✗ Co in AuCo = allergenic! EU watch list
✗ Not Wire Bondable (Co/Ni = interface contamination)
▶ YouTubeAuNi = alternative (Ni-free option = AuCo)
✓ ↑↑wear resistance vs Soft Gold
✓ 50K+ insertion/extraction cycles
✗ Co in AuCo = allergenic! EU watch list
✗ Not Wire Bondable (Co/Ni = interface contamination)
Gold Plating — Jewelry & Luxury
10K/14K/18K/24KVermeilGold Fill
Gold Plate0.5-2.5 μm on Base Metal (Brass/Cu)
Gold Fill5-100μm! = 5% Au weight (MIL Standard)
Vermeil2.5μm+ Au on Sterling Silver 925
10K41.7% Au — cheap, durable
18K75% Au — luxury, soft
24K99.9% Au — soft, expensive, not for hand jewelry
Gold Plate vs Gold Fill: Fill = 10-40× thicker! More durable
Vermeil = gold on silver = beautiful + RoHS (no Ni base)
✓ Gold Fill: ISO 8442 / US FTC Standard
✗ Gold Plate: ↓↓durability. Lasts 1-2 years
✗ 24K = too soft for hand rings — 18K/14K preferred
▶ YouTubeVermeil = gold on silver = beautiful + RoHS (no Ni base)
✓ Gold Fill: ISO 8442 / US FTC Standard
✗ Gold Plate: ↓↓durability. Lasts 1-2 years
✗ 24K = too soft for hand rings — 18K/14K preferred
Silver Plating — Bright/Matte
107% IACSMaximum ConductivityTarnish!
Conductivity107% IACS — highest of any metal!
Thickness2-25 μm (bolts: 5-8μm, RF: 5-25μm)
HardnessHV 90-130 (Bright) / HV 50-70 (Matte)
BathCyanide AgCN / Non-Cyanide (Succinimide)
UseRF connectors, antennas, BusBar, Transformers
StandardASTM B700 / MIL-QQ-S-365
Ag2S = Tarnish! Don't store near H2S/SO2 (city air)
Anti-Tarnish: Chromate/Benzotriazole coat afterward!
✓ Conductivity: Ag>Cu>Au>Al
✓ RF @ GHz: Skin Depth! Ag replaces Au in RF
✗ Fast Tarnish = ↑contact resistance ↓RF performance
✗ Not for contact with H2S, laundry, chlorine pools
▶ YouTubeAnti-Tarnish: Chromate/Benzotriazole coat afterward!
✓ Conductivity: Ag>Cu>Au>Al
✓ RF @ GHz: Skin Depth! Ag replaces Au in RF
✗ Fast Tarnish = ↑contact resistance ↓RF performance
✗ Not for contact with H2S, laundry, chlorine pools
Silver vs Gold — Selection Guide
ComparisonRFPCB
Au@PCBENIG: Solderable + Oxidation-free
Au@ContactsHard Gold AuCo: Wear resistance
Au@Wire BondSoft Gold 99.9%: Bondable
Ag@RFSkin Depth 1-10GHz: Ag > Au (cheaper!)
Ag@BusBarconductivity + cost: Ag > Au
Ag@Anti-tarnishAg + Anti-Tarnish Coat = Storage OK
RF @ high freq: Skin Depth ↓ = Ag is sufficient! No need for Au
✓ Ag = 30-40% cheaper than Au, higher conductivity!
✓ Au = Tarnish-free forever. Ag = Tarnishes
✗ Au is not more conductive than Ag — the opposite!
▶ YouTube✓ Ag = 30-40% cheaper than Au, higher conductivity!
✓ Au = Tarnish-free forever. Ag = Tarnishes
✗ Au is not more conductive than Ag — the opposite!
Cadmium Plating
AMS 2400SacrificialAerospace Only
Thickness5-25 μm
Salt Spray500-1000h
StandardAMS 2400 / MIL-C-8837
Useaerospace/defense — Ti, Al bolts
Excellent lubricity with Ti/Al. Cd doesn't cause HE!
✓ Aerospace Ti bolts
✗ Cd = Carcinogen! REACH Annex XVII
▶ YouTube✓ Aerospace Ti bolts
✗ Cd = Carcinogen! REACH Annex XVII
Black Nickel Plating
HV 150-300Ni-Zn/Ni-SnAesthetic
CompositionNi-Zn (20-30% Zn) / Ni-Sn (30-35% Sn)
Thickness2-10 μm (on bright Ni base)
HardnessHV 150-300
Coloruniform black/dark grey — matte or satin
Salt Spray48-96h (on Ni base)
Useoptics, watches, camera equipment, firearms, furniture
StandardASTM B689 / MIL-C-14538
Structure: Bright Ni (2-5μm) → Black Ni (2-5μm) on top. Black Ni = Ni-Zn/Ni-Sn composition that absorbs light.
Reflectivity: <5%! Completely matte-black finish — ideal for optics.
✓ Luxurious black aesthetic. Extreme reduction in reflection.
✓ Common in photography equipment (camera bodies, lenses) and watches.
✓ ↑corrosion resistance from Ni base + Black Ni combo.
✗ Relatively brittle — not for repeated friction.
✗ HE: steels HRC>35 — Baking 190°C/23h mandatory!
▶ YouTubeReflectivity: <5%! Completely matte-black finish — ideal for optics.
✓ Luxurious black aesthetic. Extreme reduction in reflection.
✓ Common in photography equipment (camera bodies, lenses) and watches.
✓ ↑corrosion resistance from Ni base + Black Ni combo.
✗ Relatively brittle — not for repeated friction.
✗ HE: steels HRC>35 — Baking 190°C/23h mandatory!
⚠ Hydrogen Embrittlement — HE
Electroplating = H2 forms = absorbed into steel = delayed fracture!
Steels at risk: HRC>35 / RM>1000 MPa
Prevention: Baking 190°C/23h within 4h of plating (AMS 2759/9)
Alternatives: HVOF / Electroless Ni / PVD
Electroplating = H2 forms = absorbed into steel = delayed fracture!
Steels at risk: HRC>35 / RM>1000 MPa
Prevention: Baking 190°C/23h within 4h of plating (AMS 2759/9)
Alternatives: HVOF / Electroless Ni / PVD
Hard Chrome
HV 900-1100Cr(VI)!AMS 2406
StandardAMS 2406 /
Thickness12-500 μm
HardnessHV 900-1100
Useshafts, pistons, roll grinding wheels
IssueCr(VI) carcinogenic! REACH restrictions
Hard Chrome = standard for shaft and piston rebuild.
Crack network = ↑oil retention but ↓corrosion resistance
✓ Excellent dimensional restoration
✗ Cr(VI) — carcinogenic! EPA
✗ Being replaced by HVOF/EN
▶ YouTubeCrack network = ↑oil retention but ↓corrosion resistance
✓ Excellent dimensional restoration
✗ Cr(VI) — carcinogenic! EPA
✗ Being replaced by HVOF/EN
Zinc Plating
SacrificialSalt Spray 200hCheap
Thickness5-25 μm
ChromateYellow/Blue/Black Passivate after
StandardASTM B633 · ISO 4042
Usebolts, nuts, car body sheet metal
Sacrificial Anode: Zn is consumed instead of the steel!
Yellow Chromate = Cr(III) today (RoHS)
✓ Cheapest for corrosion protection
✗ Not for HCP! (Hydrogen Embrittlement RM>1000)
▶ YouTubeYellow Chromate = Cr(III) today (RoHS)
✓ Cheapest for corrosion protection
✗ Not for HCP! (Hydrogen Embrittlement RM>1000)
Electroless Nickel — EN
MIL-C-26074Perfectly UniformHV 1000
StandardMIL-C-26074 / AMS 2404
Thickness5-125 μm
HardnessHV 500 (as-plated) = HV 1000 (after 400°C!)
P%Low-P: 2-5% / High-P: 10-13% (↑corrosion resistance)
Usecomputer boards, firearms, valves
Auto-Catalytic — no current needed! Perfectly uniform.
High-P = Amorphous = non-magnetic + ↑corrosion resistance
✓ Hard Chrome substitute without Cr(VI), without HE
✓ Annealing 400°C = HV 1100
▶ YouTubeHigh-P = Amorphous = non-magnetic + ↑corrosion resistance
✓ Hard Chrome substitute without Cr(VI), without HE
✓ Annealing 400°C = HV 1100
Nickel Electroplating
HV 150-500EMI
TypesBright Ni (HV500, aesthetic) / Sulfamate (HV150, ↓stress)
UseEMI Shielding, precision interfaces, base for Cr/Au
Sulfamate = ↓Internal Stress = for delicate parts
✓ Base layer for Chrome, Gold, Silver
✗ Ni is allergenic! Not for skin-contact products
▶ YouTube✓ Base layer for Chrome, Gold, Silver
✗ Ni is allergenic! Not for skin-contact products
Gold/Silver Plating
Maximum ConductivityPCBRF
Au Thickness0.1-3 μm (Flash: 0.1μm)
Ag Conductivity107% IACS — the highest!
Au UsePCB contacts, RF, corrosion
Ag Useantennas, contacts, friction
Hard Gold (AuCo) = harder for contacts
✓ ↓contact resistance. ↑reliability
✗ Ag = Tarnish! needs protected storage
▶ YouTube✓ ↓contact resistance. ↑reliability
✗ Ag = Tarnish! needs protected storage
Cadmium Plating
AMS 2400SacrificialAerospace Only
Thickness5-25 μm
Salt Spray500-1000h
StandardAMS 2400 / MIL-C-8837
Useaerospace/defense — Ti, Al bolts
Excellent lubricity with Ti/Al. Cd doesn't cause HE!
✓ Aerospace Ti bolts
✗ Cd = Carcinogen! REACH Annex XVII
▶ YouTube✓ Aerospace Ti bolts
✗ Cd = Carcinogen! REACH Annex XVII
⚠ Hydrogen Embrittlement — HE
Electroplating = H2 forms = absorbed into steel = delayed fracture!
Steels at risk: HRC>35 / RM>1000 MPa
Prevention: Baking 190°C/23h within 4h of plating (AMS 2759/9)
Alternatives: HVOF / Electroless Ni / PVD
Electroplating = H2 forms = absorbed into steel = delayed fracture!
Steels at risk: HRC>35 / RM>1000 MPa
Prevention: Baking 190°C/23h within 4h of plating (AMS 2759/9)
Alternatives: HVOF / Electroless Ni / PVD
HVOF — High Velocity Oxygen Fuel
WC-Co↓PorosityHard Chrome Replace
Processcombustion+O2 = particles at 300-600 m/s
Thickness100-1500 μm
HardnessHV 1100-1400 (WC-Co)
Porosity<0.5% — lowest!
StandardAMS 2447
Uselanding gear, armor, turbine blades
✓ Hard Chrome substitute without Cr(VI), without HE
✓ Porosity <0.5% = dense layer
✗ Line-of-Sight only
✗ Grinding required afterward
▶ YouTube✓ Porosity <0.5% = dense layer
✗ Line-of-Sight only
✗ Grinding required afterward
Plasma Spray APS
CeramicTBCT>15000°C
ProcessDC Plasma Arc T>15,000°C = particles
MaterialsAl2O3, ZrO2 (TBC!), Cr2O3, MCrAlY
Porosity5-15%
TBCThermal Barrier Coating — ZrO2 YSZ
TBC = ZrO2+Y2O3 (YSZ) = ↓Tmetal by 150-200°C = ↑blade life
✓ Ceramic — only Plasma can do it!
✗ High porosity. Coarse Ra
▶ YouTube✓ Ceramic — only Plasma can do it!
✗ High porosity. Coarse Ra
HVAF — High Velocity Air Fuel
HVOF+Porosity<0.2%
Advantagelower temp. than HVOF = ↑density
Porosity<0.2% — better than HVOF!
MaterialsWC-Co, NiCrBSi
✓ ↑quality over HVOF at lower cost
✓ ↑Carbide retention
▶ YouTube✓ ↑Carbide retention
Arc Spray
CheapTSALarge Areas
Processelectric arc between two wires + air
MaterialsZn, Al (TSA!), SS, Cu, Babbitt
Usebridges, tanks, TSA (Thermal Spray Al)
TSA = Thermal Spray Aluminum = Sacrificial for steel
✓ Cheap and fast. Large areas
✗ High porosity. Coarse Ra
▶ YouTube✓ Cheap and fast. Large areas
✗ High porosity. Coarse Ra
| Method | Materials | Porosity% | Cost | Use |
|---|---|---|---|---|
| HVOF | WC-Co, CrC | <0.5 | high | Hard Chrome replacement |
| HVAF | WC-Co | <0.2 | medium | WC-Co ↑quality |
| APS Plasma | Al2O3, ZrO2 | 5-15 | high | TBC, ceramic |
| Arc Spray | Zn, Al, SS | 10-20 | low | TSA, bridges |
Powder Coating
VOC=0RAL/NCSBake 180°C
Processelectrostatic powder = bake 160-200°C
Thickness40-150 μm
MethodEpoxy / Polyester / Hybrid / TGIC-free / PU
Salt Spray500-2000h with Pre-treat
StandardISO 12944 · ASTM B117
Epoxy = ↑chemical resistance. Polyester = ↑UV resistance. VOC=0!
✓ Uniform finish. ↑impact resistance
✗ Baking = not for large/delicate parts
▶ YouTube✓ Uniform finish. ↑impact resistance
✗ Baking = not for large/delicate parts
Epoxy Zinc Rich Primer — ZRP
SacrificialISO 12944
Zn%80-85% Zn dry film
MechanismSacrificial — Zn is consumed instead of the steel!
Thickness60-75 μm DFT
Salt Spray1000h+ alone
ZRP = the most effective Primer for steel!
✓ Sacrificial = protects scratches
✓ Excellent base for Isocyanate/Epoxy Topcoat
▶ YouTube✓ Sacrificial = protects scratches
✓ Excellent base for Isocyanate/Epoxy Topcoat
2K Epoxy + PU Topcoat
ISO 12944 C52-Pack
StructurePrimer + Epoxy Intermediate + PU Topcoat
DFT200-350 μm total
Salt Spray1000-3000h
ISO 12944C5-M = aggressive marine
✓ ISO 12944 C5 = maximum protection
✓ Excellent UV resistance (PU)
✗ ↑VOC. Curing time. Spray skill required
▶ YouTube✓ Excellent UV resistance (PU)
✗ ↑VOC. Curing time. Spray skill required
Intumescent Paint
EI 30-120Passive
Principleheat = swells x40 = insulates the steel
EI30/60/90/120 minutes
Usesteel beams, columns, structure
StandardBS 476 / EN 13381-8
✓ Passive fire protection with no extinguishing equipment
✗ Not for humid environments!
▶ YouTube✗ Not for humid environments!
Alodine / Chem Film — Chromate Conversion
MIL-DTL-81706Conductive!Al
StandardMIL-DTL-81706 / AMS 2473/2474
Class 1A↑corrosion protection — yellow/green-gold
Class 3↓protection + ↑conductivity — clear
Thickness0.5-2 μm
CrTrivalent Cr(III) today — RoHS!
✓ Electrically conductive! EMI bonding
✓ Primer adhesion x3
✗ Moderate corrosion protection — Primer required afterward
▶ YouTube✓ Primer adhesion x3
✗ Moderate corrosion protection — Primer required afterward
Manganese Phosphate
MIL-DTL-16232Matte BlackFirearms
Processprecipitated Mn(H2PO4)2 @ 88-98°C
Thickness5-25 μm
Usefirearms, military equipment, springs
StandardMIL-DTL-16232 · TT-C-490
Mn Phosphate = matte black. ↓Glare. Oil afterward!
✓ Firearms: matte black + ↓wear
✓ Excellent base for Paint
✗ Low corrosion resistance only — oil/paint mandatory
▶ YouTube✓ Firearms: matte black + ↓wear
✓ Excellent base for Paint
✗ Low corrosion resistance only — oil/paint mandatory
Passivation SS
AMS 2700Citric/Nitric
StandardAMS 2700 / ASTM A380 / ASTM A967
MethodCitric Acid 10% / Nitric Acid 20-45%
TestCopper Sulfate Test
Purposeremoving free Fe = restoring Cr2O3
Passivation = chemical cleaning, not a coating!
After machining: Fe from tools = pitting corrosion!
✓ Mandatory after any SS machining
✗ Not a coating — provides no mechanical protection
▶ YouTubeAfter machining: Fe from tools = pitting corrosion!
✓ Mandatory after any SS machining
✗ Not a coating — provides no mechanical protection
Black Oxide
MIL-DTL-13924Oil Mandatory
ProcessNaOH/NaNO2 @ 135-150°C
Thickness1-2 μm
Salt Spray2-4h (with oil: 24h)
Usemechanical tools, springs, military equipment
✓ ↓reflection / Glare
✓ ↑lubrication (oil in pores)
✗ Very low corrosion resistance — oil mandatory!
▶ YouTube✓ ↑lubrication (oil in pores)
✗ Very low corrosion resistance — oil mandatory!
Hot-Dip Galvanizing — HDG
ASTM A123Salt Spray 1000+h50+ years
Processdip in liquid Zn at 450°C
Thickness50-200 μm
Salt Spray1000-2000h!
StructureFe-Zn Intermetallic + Zn Pure
StandardASTM A123 / EN ISO 1461
Galvanic Sacrificial: Zn is consumed = Fe protected!
Self-healing: Zn protects scratches and cuts
✓ ↑↑corrosion resistance. 50+ years
✗ Not for dimensional precision. ↑100μm change
▶ YouTubeSelf-healing: Zn protects scratches and cuts
✓ ↑↑corrosion resistance. 50+ years
✗ Not for dimensional precision. ↑100μm change
Sherardizing — Dry Zinc Diffusion
Zn PowderUniform
ProcessZn powder + heat 320°C = Diffusion
Thickness5-25 μm
Advantageuniform even in holes and corners!
Usebolts, nails, fasteners
✓ Very uniform — blind holes
✓ ↓HE vs Electroplated Zn
▶ YouTube✓ ↓HE vs Electroplated Zn
Ceramic Thermal Spray / PEO
Al2O3PEOTmax 1600°C
PEOPlasma Electrolytic Oxidation — Al/Mg/Ti = Al2O3
Thickness10-500 μm
PEO HardnessHV 1000-2000!
PEO = Al = Al2O3 formed intra-layer. Perfect adhesion!
✓ HV 1000-2000. High Tmax. Perfect adhesion
✗ Expensive equipment
▶ YouTube✓ HV 1000-2000. High Tmax. Perfect adhesion
✗ Expensive equipment
Laser Cladding — Precision Laser Welding
StelliteRepairDilution<5%
Processlaser + powder = precise layer weld
MaterialsStellite 6/21, WC-Co, Inconel 625
Thickness0.5-5 mm
Usevalves, blades, turbine parts
✓ Most precise Cladding method. Dilution <5%
✓ Repairs expensive parts instead of replacement
✗ Expensive equipment. Slow for large areas
▶ YouTube✓ Repairs expensive parts instead of replacement
✗ Expensive equipment. Slow for large areas
Thermal Spray Aluminum TSA
SacrificialNORSOK M-501Marine
ProcessArc Spray / Flame Spray = Al on steel
Thickness100-300 μm
StandardNORSOK M-501 / AWS C2.23
Usebridges, oil platforms, marine structures
✓ ↑marine corrosion resistance x2 vs HDG
✓ Sealer afterward = perfect
✗ Porosity = Sealer mandatory
▶ YouTube✓ Sealer afterward = perfect
✗ Porosity = Sealer mandatory
ENIG — Electroless Ni/Immersion Gold
PCBIPC-4552RoHS
ProcessElectroless Ni 3-5μm + Immersion Au 0.05-0.1μm
StandardIPC-4552 / IPC-7711
UsePCB Surface Finish — the most common!
Ni = Barrier + Au = Oxidation protection
✓ The most common PCB Surface Finish RoHS
✗ Black Pad = Ni Corrosion = contact failure!
▶ YouTube✓ The most common PCB Surface Finish RoHS
✗ Black Pad = Ni Corrosion = contact failure!
📊 Quick Coating Selection Guide
| Base Material | Moderate Corrosion | Marine Corrosion | Wear Resistance | Aesthetics | Defense/RoHS |
|---|---|---|---|---|---|
| Steel | Zn Plate + Yellow | HDG + Marine Paint | Hard Chrome / HVOF WC-Co | Powder Coat | Zn-Ni Plate |
| Stainless | Passivation AMS2700 | 316L + Passivation | EN Hard (HV1000) | Electropolish | Passivation |
| Aluminum | Alodine 1200+Primer | Anodize II+Seal | Hard Anodize III | Anodize+Dye | Alodine Cr(III) |
| Titanium | Passivation | Passivation | TiN/TiAlN PVD | Anodize (colors!) | Passivation |
| Copper/Brass | OSP (PCB) | Sn Plate | Ni Plate | EN/Au Flash | Sn Plate |
| Cutting Tools | — | — | TiAlN/AlCrN PVD | TiN (gold) | DLC |
⏳ Israel Lead Time (typical)
| Coating | Lead Time | Note |
|---|---|---|
| Zinc Plate | 1-2 business days | common — any plater across Israel |
| Anodize Type II | 2-3 business days | common — Tel Aviv, Haifa area |
| Hard Anodize III | 3-5 business days | less common |
| Electroless Ni (EN) | 2-4 business days | common |
| Hard Chrome | 3-5 days | Cr(VI) — restricted and declining |
| HVOF | 5-10 days | requires Grinding afterward |
| PVD TiN/TiAlN | 5-10 days | specialty shops |
| HDG | 1-3 days | for large parts |
| Powder Coat | 1-3 business days | very common in Israel |
Zinc-Nickel (Zn-Ni) — Cd replacement
AMS 2417RoHS1000h+
Composition12-15% Ni in Zn matrix
Salt Spray>1000h (Zn=200h)
HEno HE! excellent for HRC>35
StandardAMS 2417 / ASTM B841
Useaerospace bolts, landing gear, airframe bolts
✓ No HE + RoHS + Salt Spray>1000h
✓ Boeing D6-17487 / Airbus AIMS 03-08-011
✗ More expensive than Zn. Ni% controlled strictly
▶ YouTube✓ Boeing D6-17487 / Airbus AIMS 03-08-011
✗ More expensive than Zn. Ni% controlled strictly
Tin Plating (Sn)
RoHSSolderablePCB
Thickness2-25 μm
MethodsBright Sn / Matte Sn (FinePitch!)
HASLHot Air Solder Level — SAC305 RoHS
WhiskersSn Whiskers! danger for electronics
UsePCB, cans, contacts, Solderable
HASL SAC305 = RoHS. Sn Whiskers: grow over time! Short circuit risk!
✓ Solderable + cheap + RoHS
✗ Sn Whiskers — problem in defense/space
▶ YouTube✓ Solderable + cheap + RoHS
✗ Sn Whiskers — problem in defense/space
Rhodium Plating
HV 800LuxuryUV mirror
Thickness0.05-5 μm
HardnessHV 800
Price$150,000/kg!
Conductivityexcellent
Rareduces! brightens
Usejewelry, RF contacts, laser/X-ray mirrors
✓ Harder than Au, bright, Tarnish-free
✓ Reflectivity 80% for UV/X-ray
✗ Very expensive. Thin layer only
▶ YouTube✓ Reflectivity 80% for UV/X-ray
✗ Very expensive. Thin layer only
Palladium / Pd-Ni — ENEPIG
PCBWire BondENEPIG
Thickness0.1-1 μm
Pd-Ni HV400-500
ENEPIGEN + EN-Pd + Immersion Au
UsePCB contacts, Wire bonding
ENEPIG: Ni barrier + Pd + Au flash
✓ Wire bondable! No Black Pad (vs ENIG)
✗ Expensive
▶ YouTube✓ Wire bondable! No Black Pad (vs ENIG)
✗ Expensive
Decorative Chrome
Cr(III) RoHSBright Chromeon Ni
Thickness0.1-0.3 μm (on Ni)
Cr(III)Trivalent = RoHS 2024!
FinishesBlue-bright / Black Chrome / Satin
Usehandles, automotive, faucets, bathroom accessories
Decorative = Ni base + thin Cr. Cr(III) = RoHS
✓ Familiar Bright Chrome
✗ Ni is allergenic! EU REACH
▶ YouTube✓ Familiar Bright Chrome
✗ Ni is allergenic! EU REACH
Cadmium Plate vs Zn-Ni — Comparison
CdZn-NiAerospace
Cd Salt Spray500-1000h | Lubricity Ti/Al
Zn-Ni Salt Spray>1000h | no HE
Key DifferenceCd = no HE with Ti. Zn-Ni = no HE + RoHS
TrendZn-Ni gradually replacing Cd in aerospace
✓ Zn-Ni: the next generation. Boeing/Airbus approved
✗ Cd: REACH Annex XVII. Carcinogenic. Banned EU consumer
▶ YouTube✗ Cd: REACH Annex XVII. Carcinogenic. Banned EU consumer
| Coating | Salt Spray | HV | RoHS | Use |
|---|---|---|---|---|
| Zn | 24-200h | 70 | V | general bolts |
| Zn-Ni | 1000h+ | 120 | V | aerospace, Cd replacement |
| Cd | 500-1000h | 35 | X | aerospace only |
| Sn | 200-500h | 15 | V | PCB, cans |
| Rh | 3000h+ | 800 | V | luxury, RF, mirrors |
| Pd-Ni | 1000h+ | 450 | V | PCB ENEPIG |
MoS2 — Molybdenum Disulfide
Dry Lubeu=0.05Vacuum
Thickness5-25 μm
Frictionu=0.03-0.08 (dry)
Load3500 MPa Contact!
MethodsBurnished / Bonded / Sputtered
Tmax400°C (air) | 1200°C (vacuum)
StandardMIL-L-46010
MoS2 = Lamellar — layers shear easily.
Vacuum: doesn't oxidize = standard space coating!
✓ u=0.05 in vacuum. Sputtered = Ti/Al tools
✗ In humidity: u rises (MoO3). Not for electrical contacts
▶ YouTubeVacuum: doesn't oxidize = standard space coating!
✓ u=0.05 in vacuum. Sputtered = Ti/Al tools
✗ In humidity: u rises (MoO3). Not for electrical contacts
WS2 — Tungsten Disulfide
u=0.03!HV 1200Burnishing
Thickness0.5-2 μm (burnished)
Frictionu=0.03 — the lowest!
HardnessHV 1200 (harder than MoS2)
Tmax650°C (air)
MethodBurnished powder — no baking
WS2 > MoS2: lower u + higher Tmax
✓ u=0.03 — the lowest there is! No baking
✗ Thin layer = shorter service life vs Bonded
▶ YouTube✓ u=0.03 — the lowest there is! No baking
✗ Thin layer = shorter service life vs Bonded
PTFE / Fluoropolymer — Teflon Coating
u=0.04ReleaseTmax 260C
MethodSpray + Bake 230-380°C
Thickness5-25 μm
Frictionu=0.04-0.1
Tmax260°C
Usemolds (Release), pistons, food equipment
StandardFDA 21 CFR 175.300
PTFE = sticks to nothing! Lowest surface energy
✓ Release + friction + FDA food grade
✗ Cold Flow under load! Tmax 260°C
▶ YouTube✓ Release + friction + FDA food grade
✗ Cold Flow under load! Tmax 260°C
MoS2 Bonded SFL — Solid Film Lubricant
MIL-L-23398Aerospace
CompositionMoS2/graphite/PTFE + Resin binder
Thickness5-25 μm
Tmax250°C (Resin) | 400°C (inorganic)
StandardMIL-L-23398 / MIL-L-8937
Uselanding gear bolts, frames, piping, dry Start-up
Bonded = more durable than MoS2 alone
✓ MIL-spec. Aerospace and space. Low u at Start-up
✗ Limited service life under load/cycles
▶ YouTube✓ MIL-spec. Aerospace and space. Low u at Start-up
✗ Limited service life under load/cycles
BN + Graphite — High Tmax Lubricant
BNTmax 1000CHigh Temp
BN hexu=0.2 | Tmax=1000°C! | electrical insulator
BN Usefurnaces, Glass forming, High-Temp Parting
Graphiteu=0.1 | Tmax=400°C | requires humidity!
Graphite Usecasting molds, contacts, carbides
BN = the only option for T>600°C!
✓ BN = HV 1000 + Tmax 1000°C
✗ Graphite not for vacuum! Requires air/humidity
▶ YouTube✓ BN = HV 1000 + Tmax 1000°C
✗ Graphite not for vacuum! Requires air/humidity
VCI + Cosmoline — Temporary Protection
VCIStorageVolatile
VCIVolatile Corrosion Inhibitor — protective vapors
CosmolineMIL-C-11796 — thick oil/wax
Usefirearms, engines, spare parts, export
Removalsolvent / IPA / heated
✓ Excellent temporary protection. Cheap. Reversible
✓ VCI bags = contact-free
✗ Not for storage longer than 2 years (Cosmoline=10y)
▶ YouTube✓ VCI bags = contact-free
✗ Not for storage longer than 2 years (Cosmoline=10y)
| Material | u | Tmax | Vacuum | Method |
|---|---|---|---|---|
| MoS2 | 0.03-0.08 | 400°C (1200V) | V | Burnish/Sputter/Bond |
| WS2 | 0.03 | 650°C | V | Burnish |
| PTFE | 0.04-0.1 | 260°C | X | Spray+Bake |
| Graphite | 0.1 | 400°C | X | Spray/Rub |
| BN hex | 0.2 | 1000°C! | V | Spray |
| SFL Bonded | 0.05-0.1 | 400°C | V | Spray+Bake |
Parylene — CVD Conformal Coating
CVDUniformMedical
MethodCVD Vapor Deposition — no liquid!
Thickness1-50 μm — perfectly uniform!
TypesC (common) / N / D / HT (200°C)
UsePCB, medical implants, MEMS, Sensors
StandardIPC-CC-830 / MIL-I-46058
CVD = no Surface Tension = penetrates every corner!
✓ Bio-cells: Cochlear implants, pacemakers
✓ Perfect barrier for moisture + chemicals + dust
✗ Expensive. Rework: O2 Plasma / Laser
▶ YouTube✓ Bio-cells: Cochlear implants, pacemakers
✓ Perfect barrier for moisture + chemicals + dust
✗ Expensive. Rework: O2 Plasma / Laser
Acrylic AR — Cheap and Common
IPC-CC-830UV CureEasy Rework
StandardIPC-CC-830 Type AR
Thickness25-130 μm
Tmax125°C
Reworkeasy — Acetone/MEK
✓ Cheap. Fast UV Cure. Easy rework
✗ Less moisture resistant. Not for extreme environments
▶ YouTube✗ Less moisture resistant. Not for extreme environments
Silicone SR — Tmax 200°C
Tmax 200C!FlexibleLED
StandardIPC-CC-830 Type SR
Tmax200°C — highest!
UseLED, furnaces, aerospace, automotive
RiskSilicone contaminates surfaces!
✓ Tmax=200°C. Flexible. For LED
✗ Silicone contaminates! Nearby adhesion affected
✗ Rework = burning only
▶ YouTube✗ Silicone contaminates! Nearby adhesion affected
✗ Rework = burning only
Urethane UR + Epoxy ER
UR: AutomotiveER: Military
UR StandardIPC-CC-830 Type UR | Tmax 125°C
ER StandardIPC-CC-830 Type ER | Tmax 150°C | MIL-I-46058
UR Useautomotive, industrial
ER Usemilitary equipment, medical
UR: mechanical + moisture resistance. Moderate rework
ER: very rigid + chemical resistant. Rework nearly impossible!
▶ YouTubeER: very rigid + chemical resistant. Rework nearly impossible!
Fluoropolymer XR — Chemical Resistant
Tmax 260CChemical
MaterialPTFE / FEP / Fluoroethylene
Tmax200-260°C
UsePCB: oil, salt water, chemicals
✓ Maximum chemical resistance. Hydrophobic
✗ Low adhesion — surface treatment mandatory
▶ YouTube✗ Low adhesion — surface treatment mandatory
| Type | Tmax | Moisture | Rework | Cost | Use |
|---|---|---|---|---|---|
| Parylene | 125-200°C | maximum | hard | H | medical, space |
| Acrylic AR | 125°C | medium | easy | L | consumer |
| Urethane UR | 125°C | good | medium | M | automotive |
| Silicone SR | 200°C! | good | hard | M | LED, furnaces |
| Epoxy ER | 150°C | maximum | X | M | military |
| Fluoro XR | 260°C | maximum | hard | H | chemical |
Stellite 6 — Co-Cr-W
HRC 38-47ValveGalling Resist
CompositionCo-27%Cr-5%W-1.2%C
HardnessHRC 38-47
Tmax815°C
MethodsTIG / PTA / Laser / Flame
Usesteam/oil valves, pistons, Impellers
Cr Carbides = wear resistance. Galling resistance!
✓ Oil/gas valves = the global standard
✗ Hard to weld (Pre-heat). Co expensive
▶ YouTube✓ Oil/gas valves = the global standard
✗ Hard to weld (Pre-heat). Co expensive
Stellite 12/21 + NiCrBSi
HRC 30-65Self-flux
Stellite 12HRC 48-55 | ↑C = ↑Carbides = ↑wear resistance
Stellite 21↓C+↑Mo = Sour Service H2S
NiCrBSiSelf-Fluxing! HRC 30-65 | Flame+Fuse
NiCrBSi Fuse1040°C = Porosity=0!
NiCrBSi Self-Fluxing: B+Si = Flux. Fuse = maximum density!
✓ St21 = H2S resistance. NiCrBSi = flexible HRC
✗ Fuse = distortion! For simple parts
▶ YouTube✓ St21 = H2S resistance. NiCrBSi = flexible HRC
✗ Fuse = distortion! For simple parts
WC Overlay + Colmonoy
HRC 60-70Abrasion
WC OverlayHV 1500-2000 | GMAW/FCAW/Laser
ColmonoyNi-Cr-B-Si | HRC 50-60 | Ni-base
WC UseSlurry pumps, Drill bits, mining
Col UseValve seats, Ni-base alloy compatible
✓ WC = maximum abrasion resistance
✓ Colmonoy = cheaper alternative to Stellite
✗ WC is brittle! Not for chipping/impact
▶ YouTube✓ Colmonoy = cheaper alternative to Stellite
✗ WC is brittle! Not for chipping/impact
Laser Cladding — Next Generation
Dilution <5%PreciseCW Laser
ProcessCW Laser 2-10kW + powder/wire = weld
Dilution<5% (vs TIG=20%, PTA=5-10%)
MaterialsStellite 6, NiCrBSi, WC-Ni, Inconel
Thickness0.1-5mm | Ra 3-12μm (before Grind)
✓ Dilution <5% = maximum cleanliness
✓ Precise. CNC toolpaths. Repairing expensive parts
✗ Expensive equipment. Slow for large areas
▶ YouTube✓ Precise. CNC toolpaths. Repairing expensive parts
✗ Expensive equipment. Slow for large areas
PTA — Plasma Transferred Arc
PTADilution 5%Industrial
ProcessPlasma Arc + powder = Hard Facing
Dilution5-10% (better than TIG!)
Useoil drilling tools, valves, pump shafts
Advantageautomated, consistent, high uniformity
✓ PTA = the industrial standard for automated Hard Facing
✓ Controlled uniformity + dilution
✗ More expensive equipment than TIG
▶ YouTube✓ Controlled uniformity + dilution
✗ More expensive equipment than TIG
| Process | Dilution% | Cost | Ra Post | Use |
|---|---|---|---|---|
| TIG/GTAW | 20-30 | L | 6-25μm | tools |
| PTA | 5-10 | M | 3-12μm | industrial |
| Laser Cladding | <5 | H | 3-12μm | precision, repair |
| Flame Spray+Fuse | 3-5 | M | 3-6μm | NiCrBSi only |
Electropolishing
Ra -70%GMPSS/Al
ProcessH2SO4/H3PO4 + anodic DC = ↓Ra
Ra↓50-70% from current Ra!
StandardASTM B912 / SEMI F19
MaterialsSS 304/316L, Al, Cu, Ti
UseGMP (pharma/food), medical, Semi
Passivation + Deburring + finish in one step!
✓ FDA/GMP compliant. ↓bacteria
✓ Cr2O3 restored simultaneously
✗ Rounds sharp edges! H2SO4 dangerous
▶ YouTube✓ FDA/GMP compliant. ↓bacteria
✓ Cr2O3 restored simultaneously
✗ Rounds sharp edges! H2SO4 dangerous
ISF — Isotropic Superfinishing
Ra 0.05umVibratory+ChemGears
ProcessVibratory + Chemical Accelerator
RaRa 0.025-0.1μm! No Lay
Improvement↓30% friction + ↑25% Fatigue Life!
Usegears, bearings, crankshafts
ManufacturersREM Chemicals, ISF Process
No-Lay Surface = ↓↓friction + ↑↑fatigue resistance
✓ Racing, Motorsport, Aerospace Gearboxes
✓ ↑25% fatigue life, scientifically proven
▶ YouTube✓ Racing, Motorsport, Aerospace Gearboxes
✓ ↑25% fatigue life, scientifically proven
Shot Peening
MIL-S-13165Compressive↑↑ Fatigue
Processsteel/glass balls = compressive stresses
Almen StripA/N/C — intensity measurement
Improvement↑20-40% Fatigue Life!
StandardMIL-S-13165 / SAE J443 / AMS 2430
Usedrive shafts, springs, gears, compressor
Compressive Residual Stress = blocks crack propagation!
✓ ↑40% fatigue life — mandatory in aerospace
✗ ↑Ra afterward (roughens)
▶ YouTube✓ ↑40% fatigue life — mandatory in aerospace
✗ ↑Ra afterward (roughens)
Laser Peening
AMS 2546↑+DepthF-22
PrincipleNd:YAG Laser = Shock Wave = compressive stresses
Depthup to 10mm! (vs Shot=0.5mm)
StandardAMS 2546
Rano ↑Ra! (vs Shot Peening)
✓ 3× deeper than Shot. No ↑Ra
✓ F-22, Boeing 777 wings, turbines
✗ Very expensive. Unique equipment
▶ YouTube✓ F-22, Boeing 777 wings, turbines
✗ Very expensive. Unique equipment
Burnishing
↓Ra↑FatigueRoller
ProcessCarbide Ball/Roller = pressure on surface
Ra↓50-80% of Ra
MethodsRoller / Ball / Hydrostatic
HydrostaticOil pressure + Diamond = Ra 0.05μm!
✓ ↓Ra + ↑Compressive Stress with no material removal!
✓ Hydrostatic = Ra 0.05μm
✗ Only ↓Ra 70%
▶ YouTube✓ Hydrostatic = Ra 0.05μm
✗ Only ↓Ra 70%
Mass Finishing
VibratoryDeburrVolume
Vibratoryparts + Media + Compound = vibration
Centrifugal10× faster than Vibratory!
MediaCeramic / Plastic / Steel Shot / Maize
UseDeburr, ↓Ra, Burnish, Descale, Polish
✓ Automated for large volumes. Deburr+Ra+Burnish
✗ ↓dimensional precision. Lacks specific control
▶ YouTube✗ ↓dimensional precision. Lacks specific control
Abrasive Blasting
Sa 2.5/Sa 3Pre-coat
Shot Blaststeel/glass balls = ↓Ra + Compressive
Grit Blastsharp abrasive = ↑Ra + Surface Profile
Sa GradeSa 2.5=nearly clean. Sa 3=white metal
Usepaint prep (ISO 8501-1) / Thermal Spray
Grit = ↑Profile = ↑coating adhesion!
✓ ISO 8501-1 Sa 2.5 = Min for Steel+Paint
✗ ↑Ra + ↓dimensional precision
▶ YouTube✓ ISO 8501-1 Sa 2.5 = Min for Steel+Paint
✗ ↑Ra + ↓dimensional precision
Pulsed Electrochemical Machining — PECM
PECMRa 0.02um
MethodPulsed Electrochemical Machining
RaRa 0.02-0.1μm — better than standard EP!
Advantagecorners, holes, internal radii
Usemedical instruments, HPDC molds, valves
✓ Internal corners — standard EP can't reach
✓ Ra 0.02μm = record electrochemical finish
▶ YouTube✓ Ra 0.02μm = record electrochemical finish
| Process | Ra | Compressive | Dim Change | Use |
|---|---|---|---|---|
| Electropolishing | ↓50-70% | X | Tiny | GMP, medical |
| ISF | Ra 0.025μm | X | None | gears |
| Shot Peening | ↓↓ | V | None | Fatigue |
| Laser Peening | ↓↓ | V (deep) | None | aerospace |
| Burnishing | ↓70% | V | Tiny | holes, shafts |
| Mass Finishing | ↓↓ | V | Tiny | volume |
Plasma / Ion Nitriding
AMS 2759/6HV 700-1200↓Ra
ProcessN2+H2 plasma 400-600°C = N Diffusion
Layer Thickness0.1-0.8mm Diffusion Zone
HardnessHV 700-1200
White Layer↓ vs Gas Nitriding!
StandardAMS 2759/6 / MIL-S-6090
Plasma = Active Screen / DC Glow Discharge
✓ ↓White Layer = ↑fatigue resistance
✓ SS, Alloy — not possible with Gas Nitriding
✗ Expensive equipment. Batch process
▶ YouTube✓ ↓White Layer = ↑fatigue resistance
✓ SS, Alloy — not possible with Gas Nitriding
✗ Expensive equipment. Batch process
Ion Implantation
0 dim. changeN/C/B
Processions @ tens-hundreds keV = embed
Depth0.01-1 μm
Dim. Changezero! no ↑Ra
Useprecision measuring tools, medical, MEMS
IonsN+ / C+ / B+ / Ti+ / Cr+
Zero dimensional change = for critical precision parts!
✓ N+ = ↑surface HV. ↑fatigue. ↓friction
✓ Ti implants = ↓medical wear
▶ YouTube✓ N+ = ↑surface HV. ↑fatigue. ↓friction
✓ Ti implants = ↓medical wear
Pack Cementation — Aluminizing/Chromizing
Diffusion↑↑ Tmax
AluminizingAl Diffusion 900°C = NiAl/FeAl Intermetallic
ChromizingCr Diffusion = ↑corrosion + ↑hardness
SiliconizingSi Diffusion = ↑oxidation resistance
Useturbine blades (Aluminizing = Bond Coat!)
✓ Aluminizing: ↑↑Tmax = Turbine Blades
✗ Thermal distortion possible
▶ YouTube✗ Thermal distortion possible
Laser Hardening
Laser0 distortionHRC 55-65
ProcessCO2/Diode Laser = ↑local T = Self-Quench
Depth0.3-2mm
HardnessHRC 55-65
Rano change in Ra!
UseCams, Rail, machine ways, shafts
Self-quenching: cool part mass = fast Quench!
✓ ↓↓distortion vs Induction/Flame
✓ Focused = only where needed
✗ Not for large areas. High-C steel only
▶ YouTube✓ ↓↓distortion vs Induction/Flame
✓ Focused = only where needed
✗ Not for large areas. High-C steel only
PEO / MAO — Microarc Oxidation
Al/Mg/TiHV 1000-2000Ceramic!
ProcessElectric Discharge = Plasma = Al2O3/TiO2
Thickness5-150 μm
HardnessHV 1000-2000 on Al!
Usemedical Al, automotive Mg, bio Ti
Al = Al2O3 Ceramic IN-SITU = perfect adhesion!
✓ ↑↑hardness, Tmax, corrosion
✓ TiO2 PEO = Hydroxyapatite = biocompatible
✗ ↑Ra. Expensive equipment
▶ YouTube✓ ↑↑hardness, Tmax, corrosion
✓ TiO2 PEO = Hydroxyapatite = biocompatible
✗ ↑Ra. Expensive equipment
Boronizing — Boron Diffusion
HV 1500-2000!B4C
ProcessB4C 700-950°C = Fe2B/FeB
HardnessHV 1500-2000 — harder than WC!
Useextrusion dies, casting dies, mining
✓ Maximum abrasive wear resistance!
✗ Very brittle. Not for impact! Low Kic
▶ YouTube✗ Very brittle. Not for impact! Low Kic