CoCrMo Powder

Overview of CoCrMo Powder

CoCrMo is a cobalt-chromium-molybdenum alloy powder widely used in metal additive manufacturing for biomedical, dental, aerospace, and industrial applications needing wear resistance and biocompatibility.

This article provides a detailed guide to CoCrMo powder covering composition, properties, AM process parameters, applications, specifications, suppliers, handling, inspection, comparisons, pros and cons, and FAQs. Key information is presented in easy-to-reference tables.

Composition of CoCrMo Powder

The composition of CoCrMo alloy powder is:

Element	Weight %	Purpose
Cobalt	58-69	Matrix element, biocompatibility
Chromium	26-30	Corrosion resistance, wear resistance
Molybdenum	5-7	Strength, wear resistance
Carbon	0.05-0.35	Carbide former
Silicon	1 max	Deoxidizer
Manganese	1 max	Deoxidizer
Iron	0.75 max	Contamination limit

The high cobalt content provides biocompatibility while chromium and molybdenum impart strength and wear resistance.

Properties of CoCrMo Powder

Key properties of CoCrMo powder include:

Property	Description
Biocompatibility	Excellent compatibility with human body tissues
Wear resistance	High abrasion and sliding wear resistance
Corrosion resistance	Resistant to body fluids and many chemicals
Strength	Tensile strength up to 1310 MPa when work hardened
Hardness	Up to 54 HRC when age hardened
Fatigue strength	Suitable for cyclical dynamic loading

The properties enable use for load-bearing implants and devices.

AM Process Parameters for CoCrMo Powder

Typical parameters for printing CoCrMo powder include:

Parameter	Typical value	Purpose
Layer height	20-50 Ã×m	Resolution vs build speed
Laser power	150-400 W	Melting condition without vaporization
Scan speed	400-1200 mm/s	Density versus production rate
Hatch spacing	80-120 Ã×m	Mechanical properties
Supports	Tree or lattice	Overhangs, internal channels
Hot isostatic pressing	1220¡«C, 100 MPa, 3 hrs	Eliminate porosity

Parameters tailored for density, microstructure, build rate and post-processing requirements.

Applications of 3D Printed CoCrMo Parts

AM CoCrMo components are used in:

Industry	Applications
Medical	Knee/hip implants, dental crowns, surgical tools
Aerospace	Turbine blades, engine components
Automotive	Valve seats, turbocharger wheels
Industrial	Wear-resistant tooling, flanges, seals
Oil and gas	Valve parts, pumps

Benefits versus wrought CoCrMo include complex geometries, customized implants, reduced costs and lead times.

Specifications of CoCrMo Powder for AM

CoCrMo powder must meet strict specifications:

Parameter	Specification
Particle size range	15-45 Ã×m typical
Particle shape	Spherical morphology
Apparent density	> 4 g/cc
Tap density	> 6 g/cc
Hall flow rate	> 23 sec for 50 g
Purity	>99.9%
Oxygen content	<1000 ppm

Custom size distributions and controlled moisture levels available.

Suppliers of CoCrMo Powder

Reputable CoCrMo powder suppliers include:

Supplier	Location
Carpenter Additive	USA
Sandvik Osprey	UK
Erasteel	Sweden
AP&C	Canada
LPW Technology	UK
Arcam AB	Sweden

Pricing ranges from $50/kg to $120/kg based on quality considerations and order volume.

Handling and Storage of CoCrMo Powder

As a reactive material, careful CoCrMo powder handling is essential:

• Store sealed containers away from moisture, acids, ignition sources
• Prevent exposure to air and use inert gas padding
• Ground equipment to dissipate static charges
• Avoid dust accumulation and use dust extraction
• Local exhaust ventilation recommended
• Follow safety data sheet precautions

Proper techniques ensure optimal powder condition.

Inspection and Testing of CoCrMo Powder

Quality testing methods include:

Method	Parameters Tested
Sieve analysis	Particle size distribution
SEM imaging	Particle morphology
EDX	Chemistry and composition
XRD	Phases present
Pycnometry	Density
Hall flow rate	Powder flowability

Testing per ASTM standards verifies powder quality and batch consistency.

Comparing CoCrMo to Alternative Alloy Powders

CoCrMo compares to other alloys as:

Alloy	Biocompatibility	Strength	Cost	Printability
CoCrMo	Excellent	Medium	Medium	Good
Titanium Ti64	Good	Low	High	Fair
Stainless steel 316L	Good	Medium	Medium	Excellent
Inconel 718	Poor	High	High	Good

CoCrMo provides the best combination of biocompatibility, strength, and printability for many applications.

Pros and Cons of CoCrMo Powder for AM

Pros	Cons
Excellent biocompatibility and corrosion resistance	Limited high temperature capability
Very good wear and abrasion resistance	Susceptible to porosity during printing
Readily 3D printable and weldable	Requires controlled atmosphere handling
Cost advantage versus titanium alloys	Post-processing often needed
Can match wrought material properties	Lower fracture toughness than stainless steels

CoCrMo enables functional metal implants and components, albeit with controlled processing requirements.

Frequently Asked Questions about CoCrMo Powder

Q: What particle size range works best for 3D printing CoCrMo alloy?

A: A typical range is 15-45 microns. It provides good powder flowability combined with high resolution and density.

Q: What post-processing methods are used on CoCrMo AM parts?

A: Hot isostatic pressing, heat treatment, surface machining, and polishing are commonly used post-processes for achieving full density and surface finish.

Q: Which metal 3D printing processes are compatible with CoCrMo alloy?

A: Selective laser melting (SLM), direct metal laser sintering (DMLS) and electron beam melting (EBM) can all process CoCrMo powder.

Q: What industries use additively manufactured CoCrMo components?

A: Medical, dental, aerospace, automotive, oil and gas, and industrial sectors benefit from 3D printed CoCrMo parts.

Q: Does CoCrMo require support structures during 3D printing?

A: Yes, supports are needed on overhangs and internal channels to prevent deformation and allow easy removal after printing.

Q: What defects can occur when printing CoCrMo powder?

A: Potential defects are porosity, cracking, distortion, incomplete fusion, and surface roughness. Most can be prevented with optimized parameters.

Q: What type of biocompatibility testing is done on CoCrMo alloys?

A: Cytotoxicity, sensitization, irritation, systemic toxicity, genotoxicity, and implantation testing per standards like ISO 10993 are conducted.

Q: How are the properties of printed CoCrMo compared to cast alloy?

A: AM CoCrMo components can achieve mechanical properties on par or better than cast and annealed counterparts when optimized.

Q: What are the main differences between CoCr F75 and SP2 alloys?

A: F75 has higher carbon for better machinability while SP2 has lower carbon plus niobium for improved particle melting behavior during printing.

Q: What density can be expected with 3D printed CoCrMo components?

A: Density above 99% is achievable for CoCrMo with ideal parameters tailored for the alloy, matching wrought material properties.