Abstract: Method of forming different diffusion aluminide coatings on different surface regions of the same superalloy substrate involves positioning the substrate in a coating chamber having a aluminum-bearing coating gas flowing therein with a first substrate surface region enclosed in a masking enclosure having one or more coating gas entrance apertures communicating the interior of the enclosure to the coating gas in the coating chamber and with a second substrate surface region freely communicated to the coating gas in the coating chamber, and gas phase aluminizing the substrate by heating the substrate to an elevated coating temperature in the coating chamber having the coating gas therein to concurrently form an outwardly-grown diffusion aluminide coating on the first substrate surface region and to form an inwardly-grown, diffusion aluminide coating on the second substrate surface region of the same substrate.

Abstract: Method for forming on a superalloy or other metallic substrate a platinum graded, outward single phase diffusion aluminide coating on a surface of the substrate by depositing a layer comprising Pt on the substrate and then gas phase aluminizing the substrate in a coating chamber having a solid source of aluminum (e.g. aluminum alloy particulates) disposed therein close enough to the surface of the substrate to form at an elevated substrate coating temperature a diffusion aluminide coating having an inner diffusion zone and outer additive single (Ni,Pt)Al phase layer having a concentration of platinum that is relatively higher at an outermost coating region than at an innermost coating region adjacent the diffusion zone.

Abstract: A hafnium nitride coating is applied over the cubic boron nitride layer of conventional CBN tools by the process of arc physical-vapor-deposition at temperatures below the tempering temperature of the core metal. The hafnium nitride coating protects the cubic boron nitride or diamond abrasive and the core, resulting in a grinding tool with greater strength and longer life.