PSI - Issue 32

V.B. Dementyev et al. / Procedia Structural Integrity 32 (2021) 291–294 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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compatibility with tool material (crystallochemical similarity, optimum physical and mechanical properties, decreased tendency to liquid-phase reactions and formation of intermetallic compounds) and the presence of functional characteristics (high hardness, resistance to oxidizing and high-temperature creeping, low tendency to destruction). The next compounds have found wide use both as separate coatings and as coating layers [4-7]: TiN Simple production technology, low cost, hardness is in the range of 22…24 GPa НV, coefficient of friction against steel is 0,55. This compound is used during cutting of structural steels and machinable alloys Brittle material that has reduced resistance to oxidative wear, its hardness is 37 GPa HV, low coefficient of friction against steel - 0,25. This material is used for finish machining of structural steels and machinable alloys Characteristic feature is formation of Al2O3 layer during cutting process, thus providing thermal barrier on the surface. This material has increased resistance to oxidative wear, its hardness is reaches 37 GPa HV, coefficient of friction against steel is 0,6. It is used for operations with high thermal loads, high-speed machining, machining of materials with reduced thermal conductivity and hard materials This compound has high plasticity and tribological properties. Its hardness is about 14 GPa according to Vickers, coefficient of friction against steel is 0,3. This material contributes to reduction of sticking of the material of workpiece to the tool. It is recommended to be used during machining of the soft materials (aluminum, copper and alloys on their base). Tribological coating with small hardness and friction coefficient of 0,05. It is used for machining of non-ferrous materials and alloys More plastic than TiN, which provides safe use in conditions of impact loads and big cross sections of layer to be cut This compound has increased hardness up to 37 GPa HV, which remains the same under high temperatures of cutting. It is very brittle and has increased passivity to machined materials. It serves as barrier layer, which prevents cutting edges of tools from oxidizing and corrosion under high temperatures The hardness of the material is within the range of 38 – 32GPa, it is more brittle and crystallochemically compatible with solid alloys. Usually this compound is used as underlying layer for internal layer of coating to increase adhesion strength. Current technologies of applicaton of coatings allow formation of multiphase single-layer nanocoatings. This is reached when a thin layer of the second nanocrystalline or amorphous phase is located at the boundary of the main solid nanocrystalline phase, which prevents the growth of grains of the main phase. By varying the composition of coatings we can regulate brittleness, hardness and coating thickness, keeping the size of grains the same. For example, coatings TiN-Cu, AlN-Cu, CrN-Ni and etc. can be used. The use of alternating layers of multiphase coatings (TiN NbN, (Ti,Al)N-CrN and etc.) leads to a decrease in grain size and causes the growth of hardness. Currently, there are two main methods of coating application that are used in tool production: Chemical Vapour Deposition (CVD) and Physial Vapour Deposition (PVD), which form thin film on all types of materials, except carbon steels and alloy steels. 2. Study of multicomponent coatings The productivity and economic efficiency of mechanical machining of materials with allowance removal directly depends on the nature of interaction of tool with machined material in the zone of their contact. The possibility to increase the mentioned parameters of mechanical machining processes greatly depends on the wear of the cutting surface of the tool. The properties of initial tool material are not always sufficient to provide high-efficiency machining of materials. One of the methods allowing an increase in wear resistance and a decrease in tool consumption is covering the work surfaces by wear-resistant coatings. One of the ways to decrease tool consumption is the use of specific methods for improvement of tool cutting ability. The main direction of increasing the resistance of tool materials to wear without worsening of their strength is invention and development of new technologies of creation of wear resistant coatings, primarily, refractory ones. TiCN TiAlN CrN MoS2 (Ti, Cr)N Al 2 O 3 Ti С