SINTS MIM Wear Resistance

【 Wear resistance of MIM alloys 】

 

Wear is the gradual loss of mass of a material due to the relative movement of two or more surfaces. The wear of materials belongs to the research object in the field of tribology, including friction, wear and lubrication. For many years, tribology has focused on the optimization of mechanical systems, which involves the characterization of friction characteristics, part design and lubrication. An important topic is the relationship between the friction and wear behavior of materials and the inherent properties and microstructure of materials. Although the wear resistance of a material depends on its hardness and toughness, the wear resistance can vary greatly under the same hardness conditions. In other words, the same mechanical properties, different microstructure may produce different friction and wear behavior. Powder metallurgy technology is flexible and unique, and can produce the composition and microstructure that people need to meet the performance requirements of friction and wear. This is difficult or impossible to achieve with traditional methods.

 

Engineering materials for wear conditions include a variety of metal alloys, ceramics and polymers, and an increasing number of engineering materials and mechanical parts are being manufactured by powder metallurgy. Wear resistant materials manufactured by powder metallurgy should be the object of study. However, it is quite difficult to cover all the materials. Therefore, only the effects of properties and microstructure on wear were studied. These effects are unique factors in powder metallurgy materials.

There are two ways to reduce wear: reducing friction between objects and improving the wear resistance of materials. Adding wear-resistant elements to the material can effectively reduce sliding wear. Friction can be reduced by lubricants or changes in material composition.

 

【 Wear classification 】

According to its mechanism, there are four main types of wear: adhesive wear, abrasive wear, surface fatigue and tribochemical reaction. Wear can also be divided into sliding wear, rolling wear, swinging wear, impact wear and so on according to the type of relative movement between meshing surfaces.

 

1) Adhesive wear

Adhesive wear is defined as the formation and breakdown of adhesive connections between surfaces, such as cold welded connections. The occurrence of adhesive wear depends on the physical and chemical properties of the contact material.

 

2) Abrasive wear

Abrasive wear is the transfer of material caused by hard particles between or embedded on relative moving surfaces, or by hard protruding objects on one or two relative moving surfaces. The abrasive wear mechanism includes micro-grooving, micro-cutting and micro-crushing on the metal surface. Wear is further divided into two or three body wear. Wear can be described by high or low stress wear. In general, in high stress wear, the abrasive particles are crushed, while in low stress wear, the abrasive particles are not broken. Erosion is a kind of wear, which refers to the wear caused by particle impact. The impact of hard particles carried by the air stream or carried by the flowing liquid on the surface can cause erosion. The terms "planing" and "scoring" are often used to describe the wear marks left by wear.

 

3) Surface fatigue

Surface fatigue is caused by alternating loads on solid surfaces, and often occurs in the contact between flow and impact that produce alternating surface stresses. Surface fatigue wear is the formation of cracks under the surface and causes the material to peel off. The pits you usually see are typical of surface fatigue.

 

4) tribochemical reaction

Tribochemical reactions are carried out by the continuous removal and formation of reaction layers on the contact surface. For example, in the presence of oxygen, an oxide layer is formed. The reaction of the friction surface is caused by a gas or liquid in the environment.