Industries Served

Applications for thermal spray processes and materials have a broad range across all industrial sectors. Thermal spray processes are easy to use, cost little to operate, and have coating attributes that are beneficial to applications in various industries. Applications include coatings for wear prevention, dimensional restoration, thermal insulation and control, corrosion resistance, oxidation resistance, lubrication films, abrasive actions, seals, biomedical environments, electromagnetic properties, etc., and the manufacturing of free-standing components, spray formed parts, and nanostructured materials.

Thermal spray processes and deposited materials have resulted in attractive coating solutions in the aerospace, industrial gas turbine, petrochemical and gas, and automotive industries. The inherent characteristics of it's microstructure can play an important role in enhancing performance. For instance, porosity helps reduce the thermal conductivity of thermal barrier coatings in jet aircraft engines.

In the aerospace market, combustion-spray is used to apply clearance-control coatings. In the case of abradable systems, the porosity helps to weaken the cohesive strength of the coating and allows for micro-rupture of particles when in contact with the turbine blade. Some customers recognize that low-velocity combustion might not be the optimum choice of processes for an application, but they may select combustion spray anyway because of its lower cost. (Photo Courtesy of Sulzer Metco Inc.)

In some cases, design limitations of the manufacturing process may be eliminated or reduced by thermal spray post-treatments such as spray-and-fuse. In this post-treatment process, self-fluxing nickel/cobalt alloys are flame sprayed and subsequently fused by another thermal energy source, such as an oxygen acetylene torch, furnace, induction coil, or infrared heating. Self-fluxing alloys typically have small amounts of boron and silicon that help to depress the melting point, which helps these alloys to fuse and coalesce. As they fuse, the coatings form a metallurgical bond with the substrate. The coating is dense and low in porosity, and provides high inter-particle cohesive strength and substrate-to-coating adhesive strength.

Coatings that are applied by combustion spray processes and then fused are typically suitable for highly wear-resistant applications. This is important for the agricultural and glass industries in products such as agricultural blades and glass mold plungers, which require toughness and wear resistance. Blending carbides into the self-fluxing alloys can increase coating wear resistance further.

HVOF processes are suitable not only for applying tungsten carbide-cobalt and nickel chromium-chrome carbide systems, but also for depositing wear and corrosion resistant alloys such as Inconel (NiCrFe), Triballoy (CoMoCr), and Hastelloy (NiCrMo) materials. HVOF MCrAlY coatings and some low-pressure plasma (LPPS) coatings are used for high temperature oxidation/hot corrosion and TBC bond coat applications for repair and restoration of existing components. Low melting-point ceramics such as alumina and alumina-titania are also applied via some HVOF processes for abrasive wear and dielectric applications.

Wear resistant coatings are used in nearly every industry to extend the surface life of a component. Because thermal spray coatings offer superior properties, competitive costs, and environmentally friendly processing, they are increasingly being used in place of hard chrome plating. Today, HVOF materials are being applied to hydraulic rods, landing gears, and the internal diameter of large bore cylinders as hard chrome replacements. The HVOF spraying of carbide materials on the landing gears of commercial airliners has been approved for use. Although original equipment manufacturers (OEMs) still require LPPS coatings on critical applications in many aerospace and industrial gas turbine applications, HVOF MCrAlY usage has increased for repair applications.

The wire arc process is used in aerospace for dimensional restoration and repair of many different types of jet engine components. Other applications include the spraying of bridges and marine structures with zinc and aluminum. In the paper and pulp industry, wire arc sprayed coatings are used to protect boiler tubes against hot corrosion. Medical applications are being developed such as the spraying of titanium for inert environments and rapid prototyping. Engine components that require very thick deposits to comply with specific part restoration requirements such as flanges, lugs, faces, and shafts are being coated using wire arc spray. Applications also include automotive/marine diesel components, where low-carbon steel, molybdenum, and other types of corrosion/scuff-resistant alloys are being considered for valve lifter and piston ring applications.

Applications for LPPS or VPS coatings, which typically have high bond strengths, very low levels of porosity, and less oxide content, include bond coats for thermal barrier coatings, oxidation and hot corrosion protection of blades, vanes, and buckets, biocompatible coatings for medical implants, and tungsten-rhenium x-ray targets.

Carbide coatings have been applied in the aerospace, industrial gas turbine, and a variety of industrial areas by the detonation gun process to components with excellent bond strength, hardness, and density.