Chromium CoCr Powder

Overview

Chromium CoCr powder, also known as cobalt-chromium powder, is a specialized metal powder used in various industrial applications such as metal 3D printing, surface coating, and the manufacturing of medical implants.

It is an alloy composed primarily of cobalt and chromium, with additional elements like molybdenum, nickel, iron, manganese, and silicon added in smaller quantities. The exact composition can be customized as per application requirements.

Chromium CoCr alloys are valued for properties like high strength, corrosion resistance, biocompatibility, and wear resistance. The powder metallurgy process allows components with complex geometries to be manufactured from this material.

Composition

Typical Composition Range of Chromium CoCr Powder

Element	Weight %
Cobalt (Co)	40-65%
Chromium (Cr)	19-30%
Molybdenum (Mo)	0-10%
Nickel (Ni)	0-1%
Iron (Fe)	0-5%
Manganese (Mn)	0-1%
Silicon (Si)	0-1%
Carbon (C)	0-0.75%
Other trace elements	0-1%

The ratio of cobalt to chromium can be adjusted based on whether wear resistance or corrosion resistance is more critical for the application. Higher chromium content improves corrosion and oxidation resistance. Higher cobalt provides better wear properties.

Custom alloys can also be produced with non-standard compositions tailored for specialized applications in industries like aerospace, energy, and electronics.

Production Process

Chromium CoCr powder is manufactured through a gas atomization process in which the liquefied alloy is hit by high-pressure jets of inert gas like argon or nitrogen. This breaks the molten stream into very fine droplets that solidify into spherical powders.

The particle size distribution can range from 10 microns to over 100 microns based on requirements. Finer powders provide better sintering, while coarser particles improve powder flow characteristics.

Gas atomized CoCr powders have higher purity, more uniform composition, consistent particle sizes, and better flow compared to water atomized variants. However, they tend to be 15-20% more expensive due to higher production costs.

Properties

Physical and Mechanical Properties of Chromium CoCr Powder

Property	Description
Particle morphology	Predominantly spherical with some satelliting
Apparent density	Around 4 g/cc
Tap density	Up to 5.2 g/cc
Flow rate	Fairly free flowing > 1.25 g/s
Specific heat capacity	Around 0.44 J/g-°C
Melting point	1260-1450°C
Tensile strength	Up to 1310 MPa
Yield strength	Up to 1210 MPa
Elongation	8-16%
Hardness	Up to 50 HRC

CoCr alloys deliver an excellent combination of high strength and hardness coupled with reasonable ductility. The properties can be customized by tweaking the relative composition of elements.

Characteristics

Special Characteristics of Chromium CoCr Alloy Powder

• Outstanding corrosion and wear resistance – Protective chromium oxide layer resists chemical attacks. High hardness retains dimensional integrity.
• Excellent biocompatibility and bio-inertness – Does not produce adverse reactions when used in medical implants.
• Retains strength and performance at high temperatures – Service temperature rating exceeds 800°C.
• Can be easily sterilized using normal hospital procedures.
• Lower density compared to alternatives like stainless steel – Lightweight constructs possible.
• Properties like hardness, corrosion resistance, etc. can be selectively enhanced.
• Powder production method allows very fine control over composition and size distribution.

These characteristics of chromium CoCr make it suitable for niche applications where regular alloys might struggle in terms of performance or safety.

Applications

Typical Applications of Chromium CoCr Powder

Industry	Application Areas
Aerospace	Turbine engine components, landing gear parts
Automotive	Valve seats and guides, turbocharger parts
Energy	Coal gasification, nuclear and solar components
Industrial	Thermal spray coatings, tooling jigs and fixtures
Medical	Dental implants, orthopedic implants, prosthetics
Oil and Gas	Ball valve balls and seats, downhole tools

Other niche applications include electrical contacts, welding rods, jewelry, magnets, coins, ammunition, fasteners, cutting tools, etc.

The biocompatibility and corrosion resistance is leveraged for manufacturing critical aircraft components as well as load-bearing medical implants like hip and knee joints.

Additive manufacturing provides greater design freedom to use CoCr constructs even in complex geometries needed for patient-specific implants.

3D Printing with Chromium CoCr Powder

Advantages of Metal 3D Printing Using Chromium CoCr Feedstock

• Wide range of achievable mechanical properties – As high as cast or forged equivalents
• Fabrication of patient-specific implants suited to anatomy
• Products with complex interior features like lattice structures
• Limited part quantities with no requirement for tooling
• Reduced waste generation owing to additive nature
• Conformal cooling channels can be incorporated into parts
• Allows lightweight, optimized designs not feasible otherwise
• Shorter time to market for custom products

Both laser powder bed fusion (L-PBF) and binder jetting can process Chromium CoCr powder. L-PBF offers better properties while binder jetting enables larger construcs.

Specifications

Typical Size Distribution and Grades of Gas Atomized Chromium CoCr Powder

Particle Size (microns)	Size Distribution	Common Grades
<20	Used for binder jetting	CCo-20, CoCr-20s
20-45	Suitable for most LPBF processes	CCo-28, CoCr-28M
45-100	Optimal flow properties	CCo-45, CoCr-45H
>100	For thermal spray applications	CCo-106, CoCr-106

Finer powders provide higher resolution while coarser particles improve flow. Size can be optimized for parameters like layer thickness, surface finish, build speed, and post processing needs.

Relevant Standards for Composition and Manufacturing

• ASTM F75, ISO 5832-4, 5832-12: Alloy composition for cast cobalt-chromium surgical implants
• ASTM B348: Standard specification for titanium and titanium alloy powders
• ASTM F3055, F3056: Specifying characteristics of additive manufacturing metal powders

Suppliers and Pricing

Indicative Pricing Range of Gas Atomized Chromium CoCr Powder

Condition	Price Range
Vacuum packed	$50 – $150 per kg
Inert gas sealed	$60 – $200 per kg

Pricing depends strongly on order volume, particle size distribution, gas atomization method (air or argon), and quantity of trace elements.

Some Leading Suppliers

• Carpenter Additive
• Sandvik Osprey
• Praxair
• Hoganas
• LPW Technology
• Erasteel

Cobalt alloys face variable raw material supply and extreme price volatility. Long term supply contracts are advisable for volume buyers.

Comparison With Alternatives

How Chromium CoCr Compares to Tool Steel and Stainless Steel Powders

Parameter	Chromium CoCr	Tool Steel	Stainless Steel
Density	Low	Medium	Higher
Hardness	High	Very high	Medium
Strength	High	Medium	Medium
Corrosion Resistance	Excellent	Poor	High
Wear Resistance	Excellent	Good	Medium
Bio-inertness	High	Unproven	Moderate
Raw material cost	High	Low	Medium
Thermal properties	Better	Poor	Moderate
Manufacturability	Complex	Moderate	Easy

Tool steels have outstanding hardness and can be alternative wear-resistant substitutes if biocompatibility is unimportant. Stainless steels are cheaper and adequate for normal corrosion protection needs.

For critical applications demanding reliability, performance, and safety, Chromium CoCr outperforms regular iron and steel alloys on multiple counts. The higher price tag is justified for unique use cases.

FAQ

What is Chromium Cobalt (CoCr) powder?Chromium Cobalt (CoCr) powder is a metal alloy powder composed primarily of chromium and cobalt. It is known for its excellent corrosion resistance, high-temperature stability, and biocompatibility.What are the main properties of Chromium Cobalt (CoCr) powder?Chromium Cobalt (CoCr) powder exhibits high strength, hardness, corrosion resistance, and biocompatibility, making it suitable for various applications.What are the common applications of Chromium Cobalt (CoCr) powder?CoCr powder is commonly used in industries such as aerospace, medical, and dental. It is used in the production of aircraft engine components, orthopedic implants, dental prosthetics, and more.Is Chromium Cobalt (CoCr) powder safe for medical implants?Yes, CoCr is considered a biocompatible material and is widely used in the medical field for implants such as hip and knee replacements.What are the advantages of using Chromium Cobalt (CoCr) powder in aerospace applications?CoCr’s high-temperature stability and corrosion resistance make it ideal for aerospace applications, including the manufacturing of jet engine components and gas turbine parts.know more 3D printing processes