Modern ceramic cutting tool materials are one of the most promising tool materials for the 21st century. It has been developed from the earliest pure Al23 ceramics to the addition of various oxides, nitrides, carbides, and borides such as TiC, TiN, TiB2, SiC, (W, Ti)C, Ti(C,N), WC, and Z1O2 and other multi-phase ceramic tool materials, and in material properties and applications, and many other aspects have made great progress based on the detailed study of the tool material in the cutting of cast iron wear performance and wear mechanism, a new ceramic tool material The further promotion and application laid a good foundation.
2 Test conditions The cutting test was carried out on a CA6140 machine tool. The workpiece material was gray cast iron HT300 with a hardness of 200 ~ 250 HB. The tool material used was Al23/SiCAW, Ti)C multiphase composite ceramic tool material, represented by ASW. In order to facilitate the comparative analysis, Al23/SiC and Al23AW, Ti)C two-phase composite ceramic cutting tool materials were used at the same time, and were represented by AS and AT respectively. The tool geometry angle is Y = -5°a = 6. The microstructure of the tool wear surface was observed on a mTACHIS-570 scanning electron microscope. The mechanical properties of several ceramic tool materials such as manufacturing technology and machine tools are shown in the table below.
Comparison of Mechanical Properties of Several Ceramic Tool Materials Table 141 Tool Material Flexural Strength (MPa) Hardness 3 Wear Characteristics The flank wear curve when cutting grey cast iron under the cutting conditions of Cmm. It can be seen that several ceramic tool materials have good wear resistance, among which ASW tool is the best, AT tool is the second, and SiC-only alumina ceramic tool material AS has the worst wear resistance. Under the experimental conditions, the flank wear of several ceramic tool materials is relatively uniform, and the wear curves are in good agreement with the wear law.
In contrast, at higher cutting speeds and smaller depths of cut, the lb) ceramic cutting tool materials have similar wear patterns, but have different wear properties. According to the pros and cons of the flank wear performance, the order of AT is better than ASW than AS. Relatively speaking, different components have more obvious influence on the wear resistance of the material. In addition, it can be seen from the comparison of FIGS. 1a and 1b that under the latter cutting conditions, the flank wear of the corresponding tool material is greater at the same time of cutting. With different tool materials, the amount of wear increases. For ASW ceramic tool materials, the maximum flank wear at both a and 1b cutting conditions increases from 0.28mm to 0.40mm, and for AS and AT ceramic tool materials increases from 0.36mm and 0.31mm, respectively. 0.52mm and 0.35mm. 4 Abrasion Mechanism Tool wear in the form of cast iron is wear on the rake face and flank face. The main wear mechanism is abrasive wear. Studies have shown that for ceramics and other brittle materials with abrasive wear mechanisms, the wear resistance is proportional to KlC3"42. The higher the ASW, the higher the fracture toughness Kic, the lower the flank wear of hardness H. The higher the appearance, the higher the abrasion resistance of the material, and from the above table, the fracture toughness and hardness of the ASW ceramic tool material are higher than that of the other two AS and AT tool materials, so the wear resistance is the best. On the other hand, at low-speed cutting of cast iron, due to the low cutting temperature, the SiC inside the material does not react with Fe chemically, and SiC itself does not oxidize or oxidize very weakly. At this time, the adhesive wear, chemical reaction and oxidation are very weak. The proportion of wear is small, so the SiC and ASW ceramic tool materials exhibit good wear resistance.The SEM morphology of the flank wear of the ASW ceramic tool material can be seen from the traces of abrasive wear. The bond is very slight.
However, at high cutting speeds, although the wear patterns of the tool are mostly wear of the former surface and the flank surface, the adhesion phenomenon in the wear area of ​​the rake surface is greatly increased. a is the rake face wear profile of ASW ceramic tool material. Due to the high temperature action during cutting, the tendency of SiC and Fe to undergo a chemical reaction 6 increases, and the adhesion wear increases. On the other hand, dissolution wear occurs at high temperatures. It was found that 'the solubility of Fe in SiC at high temperatures is more than about two orders of magnitude higher than that in TiC and others. Therefore, due to the chemical reaction of Fe and SiC and their mutual dissolution, the content of Fe in the tool increases. This will increase the tendency of the tool to adhere to the workpiece material and will therefore be detrimental to the wear resistance of the tool.
In fact, ceramic cutting tool materials containing SiC all have this problem when high-speed machining of iron-based workpiece materials. Therefore, care must be taken when selecting tool materials. It can be considered to be used in rough machining processes such as low-speed large depth of cut, or in the processing of nickel-base alloys, because SiC-containing ceramic cutting tool materials exhibit good cutting performance when cutting pure nickel or nickel-based alloys. 83. In the design of new ceramic tool materials, the compatibility of the workpiece material and the tool material can be taken into account, so that the tool material specifically used for the machining of a certain type or several types of workpiece materials can be manufactured in a targeted manner. To address this issue, follow-up studies are ongoing.
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