Nano-TiN modified TiC-based cermets with indexable inserts Zhang Chonggao Xie Feng Yang Haidong Liu Ning (Haipu University of Technology) is a ceramic indexable insert with YT15, YT8 and unmodified HC-based cermet blades Contrasting cutting tests. The results show that the nano-TIN modified TiC-based cermet blades have excellent comprehensive cutting performance and have broad prospects for production and application. Nanotechnology is a new technology that was born and emerged in the late 1980s. The modification of existing materials by nano-powders is a hot topic at home and abroad. The addition of nanoparticles in conventional materials can greatly increase the strength, hardness, toughness of the material, and also improve the processability of the material. Adding nano-TiN powders to TiC-TiN-Ni-Mo cermets is an idea that has important implications for cermet as a tool material. 1 Effect of nano-TiN modification on mechanical properties of TiC-based cermets Powder metallurgy was used to prepare cermets. The nano-TiN powder is dispersed by ultrasonic and then added to the mixed powder to be wet-milled-dried, granulated, pressed, pressed, and sintered into a sintered compact in a vacuum furnace. It is then ground to make indexable inserts. The influence of the addition amount of nano-TiN on the bending strength, fracture toughness, and hardness of the material can be seen. It can be seen that when the added weight of nano-TiN is less than 4%, the values ​​of bending strength and fracture toughness slightly increase with the increase of the amount of addition, but the hardness does not change much. When the added amount continues to increase, all three have a significant increase. At an added weight of 6%, the fracture toughness and hardness reach the highest value. The bending strength reached the highest value when the weight was 8%, and then all three decreased. The effect of nano-T addition on the mechanical properties of the material When the weight of the nano-TiN is less than 4%, the mechanical properties change is not obvious or even decreases because the TiN nanoparticles are in the high-temperature liquid phase (mainly Ni, Ti, and part of N, C). The greater solubility of nanoparticles, coupled with the high surface energy and high surface activity of the nanoparticles, can be considered to be less residual after sintering, and therefore does not have a strong toughening effect. At the same time, due to its negative effects such as voids and impurities, the hardness of the material may decrease. As the nano TiN addition weight gradually increases, the actual nano-TiN particles in the material are increasing, and its toughness effect is gradually reflected. When the added weight of nano-TiN is more than 6%, the fracture toughness and hardness decrease and the strength increases because TiN in the TiC-based cermet may be formed with the solid solution 0, see, and formed in the TiC-based cermet. The surface, the so-called "SS" phase; may also remain as a hard phase. When it forms an SS phase, it can prevent the diffusion of elements between the hardness phase particles and the binder phase, and serves to refine the crystal grains. However, the hardness of TiN itself is lower than that of TiC, and it is easy to decompose and produce nitrogen gas at a higher temperature. Therefore, when the amount of nano-TiN is large, the strength, fracture toughness, and hardness all decrease. From the above, it can be seen that the nano-TiN addition has a certain modification effect on the material, and the mechanical properties are obviously improved. The peak value of each mechanical property corresponds to a certain amount of nano-TiN added. When the added weight is 6%~8%, better comprehensive mechanical properties can be obtained. Nano-Nan Powder Dispersion Process Nano-powder has a very small particle size, high specific surface area, and high surface activity. During the preparation process, due to van der Waals forces and Coulomb forces between particles, the particles are easily condensed and agglomerated to form secondary particles, which increase the particle size to form soft agglomerates and hard agglomerates, eventually losing the ultrafine particles. Features. Therefore, the nano-powders must be surface-treated by physical and chemical methods to make them fully dispersed in the liquid medium so as to exert the proper properties of the nano-powder. Ball mill and ultrasonic two dispersion processes. The effects of anhydrous ethyl bromide on the dispersion characteristics of the organic substances such as alcohols and other organic substances in the Ninth Five-Year Plan (990395A2) as the dispersion medium and the dispersion medium, the type and amount of surfactants, the pH value of the dispersion system, and the ultrasonic time were studied. Find out the best dispersion system components and dispersion process parameters. 3Cutability study using self-made nano-TiN modified TiC-based cermets can be transposed SNUN150416) two kinds of turning tools made of YT15 and YG8 indexable inserts with the same specifications, comparative turning test on CA6140 lathe . 31 Compared with YT15 and YG8 inserts when cutting 45 steel, the obtained wear curve. As shown in the figure, the nanometer modified tool has a much longer tool life than the YT15 tool. When the feed amount is small, the tool fails in the form of wear; when the feed amount is large, the tool fails in the form of damage. The reason for the longer tool life of the Nano TiN and YG8 tool wear curves for the nano TiN modified tools is that under dry friction conditions, the wear process of the TC-based cermet is the bond wear plus the spalling of the hard phase. This is because the TiC hardness of the main hard phase in the Ti(C,N)-based cermet is greater than that of the hard phase in the YT-based hard alloy. Furthermore, the addition of TiN inhibits the diffusion of Mo into the hard phase and W, Ti Elements such as Ni diffuse into the hard phase, which can produce significant grain refinement and increase hardness and strength, and therefore have good resistance to abrasive wear. The thermal conductivity of TC-based cermets is good, the friction coefficient with steel is small, the cutting temperature is low, and diffusion wear can be reduced. Moreover, the diffusion speed of the TC-based cermet binder Ni and hard phase TiC into the steel is less than that of Co. And WC. In addition, TC and TiN can produce a denser Ti2 film at high temperatures, which can cover the surface of the tool to further prevent the diffusion of various elements. Therefore, TC-based cermets have good resistance to diffusion wear. The formation of Ti2 films and the fine grain structure of the material also increase the tool's ability to resist sticking. Both Ni and TiN improve the corrosion resistance and chemical stability of the material in TiC-based cermets. It can be seen from the above that the nano TiN modified TiC cermet tool has a very good comprehensive cutting performance. In b, due to the large amount of feed, the load on the main cutting edge of the unit is large, and the strength and initiality of the TC-based cermet is lower than that of the YT-based hard alloy, resulting in chipping. 3.2 Comparison with ordinary HC-based cermet blades for cutting 45 steel and gray cast iron Under lran/r cutting conditions, 45 steel and gray cast iron were machined respectively, and the wear curve shown was obtained. It can be seen from the figure that nano-modified cermets have greatly improved chipping resistance and wear resistance. This is because the nano-TiN particles dispersed in the TC grain boundary have the effect of pinning the grain boundaries and preventing the growth of the TiC grains, that is, the effect of dispersion strengthening and grain refinement. The huge surface energy of the nanopowder provides sintering driving force, activates sintering, promotes diffusion and lowers sintering temperature, and is advantageous for obtaining a fine-grained structure. At the same time, TiN particles dispersed within the TiC grains also play a role of solid solution strengthening. It can be seen that nano-modified cermets are a new method of increasing ceramics. 3.3 Comparison of cutting and quenching steels Large-scale prototype precision control of melt extrusion molding TANG Guolin, WU Rendong, WEI Dazhong, LU Qingping (The Laser Rapid Prototyping Center of the Department of Mechanical Engineering, Tsinghua University) The large-scale MEM device MEM600 can produce large prototypes of 500mmX500mmX 600mm at high speed. The article mainly discusses the accuracy control of forming large parts prototypes by MEM process. Machine shell and so on. According to reports, only the MEM) process for researching and developing MEM process in China is an important process in the rapid prototyping technology, and it is on behalf of Tsinghua University. Tsinghua University has developed the MEM series forming machine. The table product is the FDM series forming machine of the Stratasys Corporation in the United States. The number of equipment tables has accounted for 70% of the entire RP industry. With the development of RP technology, the applicable field is becoming wider and wider. Among them, the forming of large-scale prototypes has gradually become an important application, such as washing machine inner barrels, TVs, where the small-scale equipment MEM-250 has been commercialized, its forming quality and precision have reached the international advanced level; large-scale equipment MEM-600 is successfully developed in the laboratory , And successfully used this equipment to produce large prototypes. Introduction to the 1MEM Process Each lamella forming part of a MEM process is formed by the accumulation of a material filament. During the forming process, the basic process of the MEM process after heating and melting of the forming material is mm, and the wear curve of the quenched 45 steel (hardened by intermediate frequency quenching, hardness 55HRC) is cut by several cutters under the conditions of feed amount/=0.1 mm/r. As can be seen from the figure, at the lower cutting speed, the TiN-modified TiC-based cermet cutting tool has good wear resistance and long service life when cutting hardened steel. Tests with a cutting speed of V>30 m/min have been used. The tool wears sharply during cutting and fails due to chipping. 4 Conclusion Through the above cutting test instructions: nano-TiN modified TiC-based cermet indexable blade with high hardness, high temperature performance and chemical stability, anti-abrasive wear, adhesive wear, diffusion wear and chemical wear ability Excellent properties, such as slightly lower toughness and strength, and poor chipping resistance, but in most cases it is better than the carbide cutting tool. Nano-TiN-modified TiC-based cermets are a new type of tool material that appeared in the 1990s, and have a series of advantages of oxidation resistance, high temperature resistance, wear resistance, etc., plus their density of 6.3~6.8g/am3, only hard With a density of 13.5 to 148g/cm3, which is the same weight as the powder, the cermet can obtain a product with twice the number of hard alloys. The use as a tool material not only prolongs the service life, but also reduces the cost. The production application has a wide range. prospect. Grease GUN SUZHOU CREATION SPACE INTELLIGENT TECHNOLOGY CO.,LTD , https://www.pkanglegrinder.com
Nano TiN modified TiC-based cermets with indexable inserts