Apex Hydraulics, U.K., has developed a Corex tungsten chromium carbide thermal spray coating that provides hardness up to 1400 HV and bond strength of about 10,000 psi. Designed to optimize durability of cylinders and pistons, porosity is less than 1% with no micro-cracks such as those associated with hard chrome plating (HCP). It also provides higher resistance to impact and wear. As a thermal spray process, it also takes less time to apply than HCP.
The Corex tungsten chromium carbide compound is an extremely hard, dense, cohesive rod coating with extremely high bond strength. Whilst outperforming HCP on the core metrics of cylinder impact, corrosion and wear, the cylinder application process for Corex is shorter in duration and provides ecological advantages over HCP.
Corex reduces by more than half theimpact damage to cylinders through small repeated impacts and large impacts. These can dent the substrate and in turn leads to cracking and peeling of the coating. Material flex in hydraulic pistons has also been carefully considered and the technology adapted to accommodate.
Utilizing thermal spraying techniques, Corex can be applied to large surface areas with a thicker coating. Not only does this reduce the application time from a full day to within hours, but also it provides a continuous surface, preventing the micro-cracks associated with HCP that lead to corrosion. HCP porosity is 5 to 10%, with additional micro-cracks.
http://www.apexhydraulics.co.uk/product/corex-coatings/
