Surfaces at the mercy of erosive or abrasive wear, extreme heat, corrosion, or require dimensional restoration or electrical insulation, as examples, can benefit greatly from high velocity oxygen fuel (HVOF) type coatings. Developed in the 1980's, this branch of thermal spray coatings brings surface property enhancements that may include: adhesive strength, hardness, and resistance to permeation or abrasion, using a wide variety of alloyed metals and ceramic powders transformed right into a plasticized state while fed by way of a temperature gas stream.
Generally known as "wire flame spray" or the "combustion wire coating process", the procedure utilizes an oxygen-fuel gas flame for heat source. Both wire form and solid rod feed-stock are used.
The outermost tip of the wire or rod is melted since it passes through the flame and is "atomized" into really small particles by way of a surrounding jet of compressed air, propelled to the work-piece to create the coating at the top.
Substrate temperatures remain lower in the HVOF coating process comparatively, little heat is imparted to the work-piece, so threat of distortion from heat is minimal, only a couple of hundred degrees F, typically, making most metals appropriate for the coating process, including: iron, steel, martensite or austenite grades of stainless, alloys of aluminum and copper. Builds (coating thickness) as high as 0.250 inch are attainable.
Additionally, the RoHS compliance of HVOF coatings brings significant advantage over metal finishing processes such as for example hard chrome plating.
Markets for high velocity oxygen fuel (HVOF) industrial coatings include: automotive, medical, aerospace and defense, paper and printing, food processing, industrial and manufacturing, military, defense and aerospace, and more.
Restoring surface dimensions of worn components is really a common usage of this coating process. However, uses involving point or line contact, shear loads, higher stress, ought to be avoided, such as for example gear teeth, threads or splines.
For newly-engineered surfaces requiring performance answers to abrasive wear, HVOF coatings predicated on tungsten carbide is definitely an excellent choice. In applications of surface fatigue, motion between contacting areas, overcoming friction associated with wear, molybdenum can serve well.
Thermal spray coatings can solve a number of issues relating mechanical, electrical, or corrosion. However, remember that no strength is put into the bottom material. Surfaces should be in a position to withstand the mechanical loads operating; heat or nitride treat as needed.