High Wear-Resistant Coatings and Surfaces
| Thermal Spray Powders
PPM Ltd.'s production facility offers components of thermal spray (HVOF, LVOF, plasma, or cold spray) powders custom produced to each individual customer's distribution specifications. The thermal spray process is the application of a spray coating to a part that requires the added properties, such as strength and hardness, of the spray coating. Powders are fed and heated to a molten or semi-molten state and accelerated towards the substrate where they adhere onto the surface. Thermal spray can produce coatings from 20 microns to several millimeters thick. Common characteristics for thermal sprayed coatings include excellent wear resistance and corrosion resistance.
Variations of thermal spraying:
High Velocity Oxygen Fuel (HVOF) Spraying
The HVOF process uses a mixture of gaseous or liquid fuel (e.g. hydrogen, kerosene) and oxygen that is fed into a chamber. This mixture is ignited and combusted such that an extremely high velocity stream is created and used to propel particles towards the substrate. At the substrate, the molten droplets flatten and solidify to form a deposit. As a result of HVOF, a coating with high density, low oxide content, and excellent bond strength is formed.
Low Velocity Oxygen Fuel (LVOF) Spraying
The LVOF process uses the same combustion process as HVOF except particles are accelerated to lower stream velocities and at lower temperatures.
In the plasma spraying process, powder or wire is fed into an extremely high temperature plasma jet. As the material enters the jet, it is melted and propelled towards the substrate. At the substrate, the molten droplets flatten and solidify to form a deposit. Plasma spraying is the most versatile of the thermal spraying processes due to the flexibility of nozzle designs, powder injection, and its wide temperature-range capabilities.
In cold spraying, particles are carried in a gas stream formed by a supersonic compressed gas jet and accelerated to extremely high velocities. Upon impact, particles with sufficient kinetic energy will undergo rapid plastic deformation and bond to the substrate. A critical velocity must be reached in order for a coating to form. This velocity is dependent on material properties, particle size, and temperature. Due to the lower temperatures, coatings with low porosity and oxygen content can be formed.
| Plasma Transferred Arc Powders
PPM produces PTA Powder blends to provide excellent wear protection for high-wear, moderate impact applications. Material applications include carbon steel, alloy and stainless steels, Monel, cast iron, nickel, and cobalt base alloys. Our powder blends have tightly controlled powder distributions designed to flow easily.
We have extensive experience and are familiar with the requirements of domestic and international hardfacing powder customers. If you have any questions, please do not hesitate to contact our capable and experienced engineering staff. Samples for qualification are available upon request.