Spray Coatings and Weld Overlays

This hardfaced coating company offers a wide range of spray and overlay services to the surface finishing industry.

The company applies three major types of spray coatings including nickel-base spray-and-fuse coating. A special alloy of nickel, chromium, silicon, boron, and carbon make up this coating type. Its major attribute, in addition to excellent resistance to galling and abrasive wear, is that its melting point is only about 2,000°F. This means that it can be sprayed onto a steel component and then subsequently fused, or melted, without melting the base metal. The company also applies plasma spray coating, which was developed to enable aerospace engineers to spray-form non-metallic nose cones. This process is used to apply high-melting materials such as chromium oxide, aluminum oxide, and titanium oxide. The company also offers high-velocity oxy-fuel (HVOF) spray. HVOF is a relatively low temperature (5,000°F) process, which accelerates spray powder to extremely high velocities. This company has two HVOF spray systems. Although they have primarily been used to apply cemented carbide materials, the HVOF process has also been used to apply Stellite, stainless steel, Hastelloy, and several other materials.

The company uses four different processes to apply weld overlays—TIG, MIG, pulsed MIG, and plasma-transfer-arc. Weld overlays offered include:

Chromium electroplate: is said to have a very good lubricity and can be finished to a very smooth surface finish.

Electroless nickel: a nickel-phosphorous overlay that can be applied to inside diameters and blind holes, is extremely uniform in thickness, can be heat treated to high hardness, and is non-conducting.

Carburizing and nitriding: carburized cases as thick as 0.125-in. can be achieved in carbon steels and alloy steels, and the component can subsequently be heat treated to develop specific properties in both the case and the base alloy. Nitrided surfaces are usually thinner, and can be used to finish-machined components without distortion or the need for post-nitride finishing.

Holtgren, 80 Milltown Road, Union, NJ 07033. Tel: 908-6862332. Fax: (908) 688-1737.