金刚石与磨料磨具工程2026，Vol.46Issue(4)：480-488,9.DOI:10.13394/j.cnki.jgszz.2025-0046
Ti-B-C三元复合陶瓷的B4C/C前驱体原位合成及性能研究
Research on in-situ synthesis of B4C/C precursors and properties of Ti-B-C ceramics
摘要
Abstract
Objectives:Metal boride/carbide ceramics possess excellent mechanical properties,and their high electrical conductivity facilitates ceramic processing.Furthermore,metal boride/carbide ceramics containing TiB ₂ additives often exhibit superior hardness and wear resistance.However,it is difficult to obtain dense sintered bodies with high hardness and strength for this type of ceramic at lower temperatures(<1 500℃).In this study,a highly active,clean carbon source is prepared by the graphitization of diamond at high temperatures.The B4C/C precursor powders are synthesized by in-situ reaction between the completely graphitized diamond and B2O3 powder.Subsequently,Ti-B-C composite ceramics are prepared at lower temperatures via reaction sintering between the B4C/C precursor powders and Ti.Methods:Diamond particles with sizes of 100,500 and 1 000 nm sizes are used to prepare precursor powders.Diamond powders are mixed with B2O3 powder in a B∶C atomic ratio of 4∶7 and then heated under vacuum in a graphite container to 1 450℃and kept for 30 min to produce highly active B4C/C precursor powders.The graphitization of diamond starts at 800℃.Before that,the heating process cleans the diamond surface,which ensures the cleanliness of the carbon source.The size of the diamond influences the size of the reaction products.Nanoscale diamonds facilitate the formation of nanoscale precursors.The B4C/C precursor powder and the Ti powder are mixed by ball milling in a mass ratio of 3∶7.The mixed powders are sintered using spark plasma sintering method at 1 200℃for 15 min to produce Ti-B-C composite ceramics.The structural and mechanical properties of the composite ceramic materials are investigated by scanning electron microscopy,X-ray diffraction and Vickers hardness testing,and the influence of diamond particle size on the microstructure and mechanical properties of the composite ceramics is analysed.Results:The X-ray diffraction results of the B4C/C precursor powders show that diamond particles in the raw material are completely graphitized during the synthesis process.As the diamond particle size increases,the graphite peak at 25.7° becomes progressively sharper,indicating that the crystallinity of graphite increases with increasing diamond particle size.No diffraction peaks of B2O3 are detected in the precursor powders,suggesting that B2O3 is completely removed during the rinsing process.The morphological characterisation results of the B4C/C precursor indicate that the particle size of the precursor powder increases with the increase in the diamond grain size in the raw material.The phase composition analysis of the Ti-B-C composite ceramics reveals that the sintered samples consist of TiC,graphite,TiB2 and a small amount of TiB.The absence of Ti phases indicates that the composition of the samples is appropriate and the system reaction within the system is complete.The microstructure of the Ti-B-C composite ceramic exhibits a three-dimensional network structure,which provides the specimens with excellent mechanical properties.The hardness test results indicate that the hardness of the samples increases with increasing diamond particle size.Conversely,the elastic recovery of the samples decreases as the diamond particle size increases.The results of the Young's modulus measurements obtained from nano-indentation testing indicate that the Young's modulus of the specimens is positively correlated with diamond particle size.The results of friction and wear experiments show that although specimens prepared from 100 nm diamonds do not exhibit outstanding hardness,their low coefficient of friction confers good wear resistance.Conclusions:In this study,B4C/C precursor powders are prepared by pressureless sintering of a mixture of diamond and boron oxide powders.Subsequently,Ti-B-C composite ceramic materials are fabricated by sintering the Ti-doped precursor powders using the SPS method.The phase composition,fracture morphology,hardness,density,Young's modulus,and coefficient of friction of the samples are tested.The results show that:(1)B4C/C precursor powders are successfully prepared via pressureless sintering;the diamond is completely graphitised,and the precursor powders consist of B4C and graphite.(2)Ti-B-C composite samples are prepared by reaction sintering between Ti and the precursor powders.The TB1000 bulk specimen exhibits the highest hardness(19.2 GPa)and the highest Young's modulus(216 GPa).As the hardness of TB100,TB500 and TB1000 differs only slightly,the specimen with the lower coefficient of friction exhibits higher wear resistance.Among these,TB100 has the lowest coefficient of friction,at 0.22.(3)Among the sintered bulk specimens,TB1000 has the highest density,with a compactness of 93%.By comparison,TB100 has the lowest density,with a compactness of only 77%.As a result,the larger the diamond particle size in the precursor powder,the higher the density and compactness of the sintered specimen.(4)The flexural strength results obtained from three-point bending tests on the TB100,TB500 and TB1000 samples indicate that the highest flexural strength of the specimens reaches 123.8 MPa,which is comparable to that of commonly used ceramic materials.关键词
Ti-B-C复合陶瓷/金刚石/放电等离子烧结/力学性能/微观结构/原位合成Key words
Ti-B-C composite ceramics/diamond/spark plasma sintering/mechanical properties/microstructure/in-situ synthesis分类
矿业与冶金引用本文复制引用
宗泳吉,李奥,李其松,穆云超,黄权,成晓哲..Ti-B-C三元复合陶瓷的B4C/C前驱体原位合成及性能研究[J].金刚石与磨料磨具工程,2026,46(4):480-488,9.基金项目
国家自然科学基金(51902358) （51902358）
国家自然科学基金项目(52472060) （52472060）
国家自然科学基金项目(51602356). （51602356）
