Hard chrome replacement: General Industry Coverage

Hard chrome plating (HCP) is the industry standard for coating parts that operate in demanding environments, such as cylinders and pistons. That coating, however, has downsides, according to James Oldroyd, managing director at Apex Hydraulics Ltd., which specializes in meeting the hydraulic requirements of the oil and gas industry.

For one, the HCP process produces hexavalent chromium, or Cr(VI), as a byproduct. As a known carcinogen, hexavalent chromium targets the respiratory system, kidneys, liver, skin and eyes. “It’s estimated that 558,000 workers are potentially exposed to Cr(VI) in the United States alone,” Oldroyd said.

Courtesy of Apex Hydraulics

A part coated with the Corex tungsten-chromium-carbide compound from Apex Hydraulics.

In addition, HCP porosity is 5 to 10 percent, and HCP experiences microcracking in all circumstances, with the amount varying based on the manufacturer, according to Oldroyd. As an alternative, Apex Hydraulics introduced the Corex tungsten-chromium-carbide compound after 2 years of R&D. Oldroyd pointed out that the dense, cohesive rod coating has a porosity of less than 1 percent, a hardness up to 1,400 HV, a bond strength greater than 10,000 psi and doesn’t experience microcracking. In comparison, HCP has a hardness of 750 to 850 HV and a bond strength of less than 5,000 psi.