Thermal spray used for mining equipment? You bet! But before you choose a thermal spray coating (also known as ‘hardfacing’), you must first understand the type of wear. The answers may surprise you.
Abrasive wear can include lower impact, lower stressed conditions. Here, there will be no fracture, no sudden loss of parent material. Rather, material removal is the result of scratching, filing, a consistent loss in metal at some micro-level. Of course, wear rates will be more dramatic when the mined abrasives are sharp, angular in nature. Proper material hardness, such as an abrasion-resistant steel or ceramic, is key.
Adhesive wear is more of a tearing or material separation between interacting surfaces. It begins with rubbing, and ends with phenomena known as scoring, galling, or seizure. Their occurrence is typically associated with like materials and structure, under an applied load, without lubrication. Here, material choices should consider attributes like ductility, for impact strength. These “softer” alloys available can actually work harden with impact or deformation. The result is increased strength and resistance to abrasion.
Have you already identified the wear mechanism? Made the proper material selection? Well, now it is time to consider thermal spraying. Hardness is the normal measurement for material choice. Again, keep in mind that, under abrasive conditions, harder material choices, like tungsten carbide or ceramic coatings are ideal. But for adhesive wear, where impact strength can be crucial to success, softer, more ductile choices are the answer.
Did you know that how (or where) the thermal spray coatings are applied can also slow down rates of wear? Depending on mined material type and shape, the success of a hardface deposit will be in how it is aligned on the surface. Parallel, perpendicular, even coating spacing and overlap can mean the difference between success and failure. Dissimilarity in thermal expansion characteristics between the coating and parent metal is also something to consider.