CHAPTER 4 INTRODUCTION TO WEAR & WEAR MECHANISMS 1
4.1 Introduction • Wear is the surface damage or the removal of the material from the surface of a solid body as a result of mechanical action of the counter body. /sliding, rolling or impact motion/. • Wear may combine effects of various physical and chemical processes proceeding during the friction between two counteracting materials: micro-cutting micro-ploughing plastic deformation cracking fracture welding and melting 3
• There are five different types of wear (wear mechanisms): adhesive, abrasive, fatigue, corrosive and erosive wear . • In many cases, the combinations of the adhesive, corrosive and abrasive forms of wear occur : two-thirds of all wear encountered in industrial situations occurs because of adhesive-and abrasive wear mechanisms. • Wear by all mechanisms except by fatigue mechanism , occurs by gradual removal of material. Objective : to understand the wear mechanisms and control methods . 5
4.2 Wear mechanisms • Wear occurs by mechanical action and is generally accelerated by frictional heating (or thermal means). • Wear includes five principal , quite distinct phenomena that have only one thing in common: the removal of solid material from rubbing surfaces. • Types of wear are: 1. Adhesive wear 2. Abrasive wear 3. Fatigue wear 4. Corrosive wear 5. Erosive wear 6
4.2.1 Adhesive wear • Adhesive wear occurs when two normally flat bodies are in sliding contact . • The load applied is so high that adhesion (or bonding) and deformation occurs at the asperity contacts at the interface, and these contacts are sheared by sliding. • The motion of the rubbing counter bodies result in rupture of the micro-joints. Thus some of the material is transferred by its counter body. 7
. metal 8
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- Fall '19
- Msc. Amar Yemim