چكيده به لاتين
Abstract
The purpose of this study is to produce NiAl-TiB2-TiC composite using the process of combustion synthesis and to investigate the factors affecting the process. Powdered raw materials including aluminum and nickel as base powders and boron carbide and titanium powders were used as reaction agents for increasing the reaction temperature, as well as for the production of ceramic phases. These powders were used to prepare Ni + Al: 3Ti + B4C powder mixtures. Became Compressed samples obtained in the Argon atmosphere were induced under high-speed heating.The effect of particle size parameters of nickel and titanium, the ratio of the weight of the exothermic agents, the applied force during synthesis and the relative density of crude on the reaction product, ignition time, microhardness and porosity were investigated. Fuzzy and microstructure synthesized specimens were evaluated by XDS and SEM equipped with EDS. Porosity percentage of samples was analyzed using Archimedes method and their distribution by visual analysis of samples. The results showed that the final product consists of three dominant phases of NiAl, TiB2 and TiC. By reducing the average particle size of nickel from 87 microns to 3 microns to increase contact surfaces, the ignition time of the samples is decreased and the samples react more strongly. Also, the hardness of the samples resulted from the fineness of the final structure from 730± 62HV100 to 890 ± 34HV100, and the porosity decreased by about 10%. Similar results were obtained for titanium particles. The result of the increase in the weight ratio of the exothermic agents in the initial composition was the reduction of ignition time and porosity increase and the hardness of the field, so that by increasing the weight percent of the exothermic agents from 5% to 45% by weight, the microhardness from 428 ± 88 HV100 to 960 ± 37 HV100 was and Porosity reached 25.8% to 46.8% .The force applied during synthesis eliminates open pores, so that by applying a 60Kg force to samples, a sample with 3.7% porosity was obtained, with increased force of time, ignition also decreased due to increased contact surface. The change in force did not affect the hardness. Increasing the relative density of raw material reduced the porosity of the secondary, so that the porosity of the samples at 65% and 95% relative density after synthesis was 58.8% and 26.9%, respectively. The variation time of the ignition timing with a relative density was at a minimum point of 85% density. No significant effect on hardness was observed with increasing density. Also, in samples with low relative density, the reaction is not completely performed.
Keywords: Dense composite, NiAl-TiC-TiB2 composite, exothermic agents, Nickel aluminide, Ceramic reinforcement
