Cincinnati Thermal Spray, Inc.
Coatings, Technology, Solutions
CHROME PLATING REPLACEMENT
Government Restrictions on Chrome Plating
For decades chromium plating has been a material of choice when building up worn components and improving wear resistance and corrosion resistance of machine elements. In recent years, chrome plating has come under attack because the plating process emits a substance called hexavalent chrome, which is considered to be a cancer causing substance. This substance is carried in the air we breathe and can also get into our water supply. There is considerable concern about people living close to chrome plating facilities.
In order to overcome this problem, regulatory agencies have instituted more stringent air quality standards resulting from the chrome plating process. These standards have required the chrome plating facilities to install increasingly sophisticated equipment to achieve compliance. The use of chrome plating is so widespread that these requirements have prompted a desire to replace chrome plating with some other coating alternative.
The governments of the U.S. and Canada have been cooperating to replace chrome plating in their activities and have created the Hard Chrome Alternative Team or HCAT — a consortium of industrial companies and government agencies with an interest in finding alternatives to the chrome plating process. Much of this activity has centered on thermal spray, and specifically HVOF as a viable alternative. The applications currently being focused on are aircraft components. For these applications, HCAT has identified three coatings — tungsten carbide/cobalt, tungsten carbide/cobalt chrome and Tribaloy™.
Chrome Plating Replacement Options
HVOF coatings have proven to be far superior to chrome plating in terms of wear resistance and equal to or better than in corrosion resistance.
In the broader world, outside the fairly narrow concerns of military requirements, the uses of chrome are many and more varied. Since thermal spray has available at least 400 different materials (alloys, pure metals, cermets, ceramics, etc.) a material can be chosen with properties tailored to a specific application. This was never possible with chrome. Chrome plating is chrome plating and properties vary within a fairly small range. Thermal spray, on the other hand, will perform well across a very broad range of service conditions and working environments. Thermal spray coatings will perform in hot environments, acidic corrosive environments, and a host of others where chrome plating would never even be considered.
Outside of rarely encountered extreme environments, CTS has found that HVOF coatings will enhance wear resistance to five or more times the wear resistance of chrome plating. In application after application, HVOF provides superior wear resistance and corrosion resistance.
|HVOF chrome replacement, CTS utilizes
cryogenic cooling to tightly control
part temperatures during processing.
|High pressure turbine disk, Tribaloy™
coating being applied with thermal
|Chrome Plating Replacement|
|Some of the coating materials that CTS specifies for chrome plating replacement are:
|Airframe Flight Systems Actuator, Triballoy™ and WC-Co-Cr HVOF coatings provide superior protection over standard Chrome plating.|