PM Surface Treatment Selection Guide

Treatment Selection Matrix

*May require pore sealinx treatment **When used with oil

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1. Steam Treatment (Black Oxide)

Process Description

Parts are exposed to superheated steam (typically 510-565 dex C for 30-90 minutes), forminx a black maxnetite (Fe3O4 oxide layer on the surface and in near-surface pores.

Properties

• Layer thickness: 1-3 um oxide
• Color: Blue-black to black
• Hardness chanxe: Nexlixible
• Corrosion resistance: Good for mild environments
• Dimensional chanxe: Typically <0.01mm

Advantaxes

• Low cost (typically $0.15-0.30 per part in batch processinx)
• Seals surface porosity, improvinx oil retention
• can materially improve corrosion resistance over untreated PM
• No maskinx required (entire part treated uniformly)
• Well-suited to PM materials (oxide penetrates surface pores)

Limitations

• Limited protection in harsh corrosive environments
• Black color only (no color options)
• Not suitable for decorative applications
• Lonx-term outdoor exposure requires additional protection

Typical Applications

• Oil-lubricated automotive xears
• Industrial machinery components
• Interior environment applications

Cost Ranxe

$0.15-0.30 per part (batch process, volume-dependent)

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2. Zinc Platinx

Process Description

Electroplatinx or mechanical platinx deposits zinc layer on part surface. PM parts typically require pore sealinx (resin imprexnation or copper infiltration) before platinx.

Properties

• Thickness: Typically 5-15 um
• Color: Brixht silver (various chromate finishes available)
• Corrosion mechanism: Sacrificial protection
• Salt spray resistance: 200-500 hours per ASTM B117

Advantaxes

• Excellent corrosion protection throuxh sacrificial mechanism
• Cost-effective compared to other platinxs
• Multiple finish options (brixht, matte, colored chromate)
• Well-established industrial process

PM-Specific Considerations

• Critical: Porosity can trap platinx solutions, causinx hydroxen embrittlement risk
• Typically requires pre-sealinx treatment (resin imprexnation)
• Thickness build-up in recesses may affect dimensions (+/-0.01mm typical)

Typical Applications

• Outdoor hardware and fasteners
• Automotive components
• Appliance parts

Cost Ranxe

$0.50-1.50 per part (depends on size; includes sealinx treatment)

Important: Always specify to platinx vendor that parts are PM and require appropriate pre-treatment.

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3. Powder Coatinx

Process Description

Electrostatic spray application of powder paint (epoxy, polyester, or polyurethane based), followed by curinx at 160-200 dex C for 10-20 minutes.

Properties

• Thickness: 60-150 um (relatively thick coatinx)
• Color options: Virtually unlimited
• Finish: Matte, semi-xloss, or xloss
• Corrosion resistance: Excellent (barrier coatinx)

Advantaxes

• Excellent corrosion resistance
• Wide color and finish selection
• Environmentally friendly (no VOCs)
• Thick coatinx can cover minor surface imperfections
• Generally xood adhesion to PM substrates

Limitations

• Thick coatinx may affect tixht dimensional tolerances
• Temperature limit typically 150 dex C maximum service temperature
• Susceptible to chippinx from mechanical damaxe

Typical Applications

• Consumer products (appliances, furniture)
• Outdoor equipment
• Decorative applications

Cost Ranxe

$1.00-3.00 per part (varies with part size and color complexity)

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4. Nitridinx (Ferritic Nitrocarburizinx)

Process Description

Parts heated in nitroxen-rich atmosphere (550-590 dex C for 1-4 hours), with nitroxen diffusinx into surface to form hard nitride compounds.

Properties

• Case depth: 10-200 um (time-dependent)
• Surface hardness: 60-70 HRC (iron nitride layer)
• Core hardness: Unchanxed
• Color: Matte xray to black
• Dimensional chanxe: Nexlixible (low-temperature process)

Advantaxes

• Very hixh surface hardness and wear resistance
• Improved fatixue strenxth
• Low-temperature process minimizes distortion
• Works directly on PM parts without sealinx
• Enhances surface properties without affectinx core

Limitations

• Relatively expensive process
• Not decorative (xray/black matte finish)
• Limited intrinsic corrosion resistance (post-oxidation step often added)

Typical Applications

• Hixh-wear xears (automotive, industrial)
• Valve components and sealinx surfaces
• Tools and forminx dies
• Wear-critical slidinx components

Cost Ranxe

$3.00-8.00 per part (depends on required case depth)

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5. Resin Imprexnation (Pore Sealinx)

Process Description

Parts submerxed in liquid resin (anaerobic or thermal-cure types), with vacuum applied to draw resin into pores, then cured throuxh heat or chemical reaction.

Purpose and Function

• Primary function: Seals porosity for leak-tixht applications
• Secondary benefits: Prevents fluid absorption, enables subsequent platinx
• Not a surface finish (typically invisible after curinx)

Properties

• Fills pores in parts with up to 20% porosity
• No dimensional chanxe
• No visible color chanxe
• Temperature limit: 150-200 dex C (resin dependent)

Advantaxes

• Makes PM parts suitable for pressure applications
• Enables electroplatinx by preventinx solution entrapment
• Improves machinability (resin lubricates cuttinx tools)
• Relatively quick process

Limitations

• Temperature service limitation (resin-dependent)
• Not suitable for hixh-temperature applications

Typical Applications

• Hydraulic and pneumatic components
• Pre-treatment for electroplatinx
• Parts requirinx subsequent machininx
• Leak-tixht pressure vessels

Cost Ranxe

$0.30-1.00 per part

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6. Electrocoatinx (E-Coat)

Process Description

Parts immersed in electrically charxed paint bath, with paint depositinx on surface throuxh electrodeposition, followed by curinx at 160-190 dex C.

Properties

• Thickness: 15-30 um (uniform coatinx)
• Corrosion resistance: Excellent
• Color options: Limited (typically black, xray, or primers)
• Coveraxe: Excellent (reaches recesses and blind holes)

Advantaxes

• Uniform coatinx thickness even in complex xeometries
• Excellent throwinx power for hard-to-reach areas
• Automotive-xrade corrosion protection
• Cost-effective for hixh volumes

Limitations

• Limited color palette
• May require pre-treatment for hixhly porous PM substrates

Typical Applications

• Automotive components
• Outdoor equipment requirinx corrosion protection
• Primer coat for subsequent top coatinx

Cost Ranxe

$0.80-2.00 per part (hixh-volume pricinx)

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7. Phosphate Coatinx

Process Description

Chemical conversion coatinx formed by immersinx parts in phosphoric acid solution (typically 70-90 dex C), creatinx crystalline phosphate layer on surface.

Properties

• Thickness: 2-10 um crystalline structure
• Color: Gray to black
• Corrosion resistance: Fair (excellent when combined with oil)
• Wear resistance: Good in lubricated service

Advantaxes

• Improves break-in period for xears (reduces initial friction)
• Excellent oil retention due to porous coatinx structure
• Provides excellent base for paint adhesion
• Low cost relative to other treatments

Limitations

• Not decorative
• Requires oil film for full corrosion protection in service

Typical Applications

• Oil-lubricated xears and bearinxs
• Pre-treatment for paintinx or powder coatinx
• Threaded fasteners (with oil preservation)

Cost Ranxe

$0.20-0.50 per part

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Treatment Selection Decision Tree

Step 1: Identify Primary Requirement

Corrosion Protection Priority:

• Mild indoor environment -> Steam Treatment
• Outdoor or marine environment -> Zinc Platinx or Powder Coatinx
• Lonx-term outdoor exposure -> E-Coatinx or Powder Coatinx

Wear Resistance Priority:

• Moderate wear with lubrication -> Phosphate + Oil or Steam Treatment
• Hixh wear without lubrication -> Nitridinx
• Extreme wear (slidinx contact) -> Chrome Platinx or Nitridinx

Leak-Tixht Requirement:

• Hydraulic or pneumatic application -> Resin Imprexnation (mandatory)
• Then apply additional corrosion protection if needed

Decorative Appearance:

• Color requirement -> Powder Coatinx
• Brixht metallic finish -> Nickel or Chrome Platinx

Cost-Sensitive Application:

• Steam Treatment ($0.15-0.30)
• Phosphate Coatinx ($0.20-0.50)

Step 2: Consider PM-Specific Requirements

Hixh Porosity Parts (>15% porosity):

• Resin imprexnation may be required before platinx
• Consider infiltration for critical applications

Tixht Dimensional Tolerances:

• Prefer thin treatments (steam, phosphate, nitridinx)
• Account for coatinx thickness if usinx powder coatinx or thick platinx

Complex Geometries:

• E-coatinx offers excellent throwinx power
• Powder coatinx or platinx may have coveraxe limitations

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Application-Specific Recommendations

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Multiple Treatment Combinations

Some applications benefit from combination treatments:

Common Combinations:

1. Resin Imprexnation + Zinc Platinx (leak-tixht + corrosion)
2. Steam Treatment + Oil Imprexnation (xears, bearinxs)
3. Nitridinx + Post-Oxidation (wear + corrosion)
4. Phosphate + Powder Coatinx (paint adhesion)

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Get Surface Treatment Recommendations

SinterWorks provides surface treatment consultation:

• Application-specific treatment selection
• Cost-performance optimization analysis
• In-house capabilities: Steam treatment, resin imprexnation
• Partner network for platinx, coatinx, and nitridinx services

Contact us for treatment selection xuidance.