Tribological Properties of Sapphire under Dry Friction against Chromium and Zirconium Ceramics

The issues of sapphire friction and wear in contact with chrome steel and zirconium ceramics are discussed in this article. The kinetic microindentation method is used to study the mechanical properties of sapphire in frictional contact in modelling experiments on the indentation of a Vickers indent. Taking into account the anisotropy of the mechanical properties of sapphire, the influence of the load and orientation of the indent on the modulus of elasticity and hardness is analyzed. It has been established that, under dry friction conditions it is promising the use of zirconium ceramics in the supports of devices operating under conditions in which the use of lubricants is impossible. The possibility of using a friction couple of sapphire-zirconium ceramics in friction units operating in open space is noted.

Kekerasan Baja Karbon Sedang dengan Variasi Suhu Permukaan Material

Beban gesek pada permukaan sebuah benda dapat menimbulkan panas pada permukaan kontak benda tersebut. Semakin besar beban gesek yang terjadi, suhu pada permukaan material akan menjadi lebih tinggi. Peningkatan suhu permukaan yang semakin tinggi dapat mempengaruhi sifat mekanis permukaan material dan tentunya dapat berimplikasi terhadap mekanisme kegagalan pada permukaan material tersebut, seperti kegagalan aus dan kegagalan retak. Pada penelitian ini, uji kekerasan dilakukan pada material dengan suhu permukaan tertentu. Permukaan material baja karbon sedang dipanaskan dengan variasi suhu yaitu mulai dari suhu kamar sampai dengan 300ºC, kemudian dilakukan uji Vicker’s. Tingkat kekerasan dan profil indentasi Vickers pada permukaan material dengan variasi suhu tersebut kemudian diinvestigasi. Friction load on the surface of an object can cause heat on the contact surface of the object. The larger the frictional load occurs, the temperature on the surface of the material will become higher. Increased surface temperatures can further affect the mechanical properties of the material surface and can certainly have implications for the failure mechanisms on the surface of the material, such as wear failure and crack failure. In this study, hardness tests were performed on materials with certain surface temperature. The surface of the carbon steel material is being heated with temperature variations ranging from room temperature up to 300ºC, then Vicker's test. The degree of hardness and Vickers indent profile on the surface of the material with the temperature variation is then investigated.