Electro-Composite Coatings for Replacement of Hard Chrome and HVOF Coatings Including Non-Line-of-Sight and Compliant Structures

US Chrome, a leading manufacturer of hard chrome plating (HCP) has been a pioneer in developing environmentally benign hard chrome replacement coatings for over two decades. These novel coatings consist of electrolytically deposited Ni, Co and Ni-Co alloy matrix containing co-deposited particles like Cr₃C₂ and SiC, targeting different aerospace applications for both structural and engine internals.

Both the alloy matrix and the particles are tailored to enhance tribological properties, abrasion, corrosion, and oxidation resistance like or exceeding those of hard chrome. They are also being used for NLOS applications replacing HVOF and intermediate temperature structural seals where HVOF coatings are too expensive.

Current applications include (i) a Co-P-Cr₃C₂ coating for actuator housing bores replacing HVOF T-400 (ii) a Co-P coating for damper housings bores replacing HCP and HVOF (iii) a Ni-Co-P coating for bladder accumulators IDs replacing HCP and (iv) a Co- Cr₃C₂ coating for high temperature structural seals for engine internals.

US Chrome is also actively pursuing a Co free Ni-P-SiC coating as a replacement for HCP for a variety of aerospace components and a Ni-W-CrAlY coating for high temperature, 1300⁰F- 1400⁰F applications.

The presentation will discuss general principles of engineering the microstructure to achieve desired properties. Wherever appropriate, specific properties like hardness, corrosion resistance (ASTM B117 salt spray test), wear and friction coefficient (ASTM G-133-65), abrasion resistance (G-65), axial fatigue (E-466) and high temperature wear test data will be presented.