【作者】 王志钢；

【导师】 朱德贵；

【作者基本信息】 西南交通大学 ， 材料学， 2005， 硕士

【摘要】 本文采用热等静压原位合成技术和过渡塑性相工艺,以TH₂、SiC和石墨粉为原料,制备了不同SiC含量的Ti₃SiC₂/SiC复相陶瓷,为扩展Ti₃SiC₂的应用提供了新的思路。通过X射线衍射、光学显微分析,分析了Ti₃Sic₂/SiC复相陶瓷材料的物相组成、晶粒大小、晶粒形貌和断裂机制。通过对其密度、显微硬度、断裂韧性、摩擦磨损性能和抗氧化性能的测试,分析了Ti₃SiC₂/SiC复相陶瓷材料的性能,表明了Ti₃Sic₂/SiC复相陶瓷材料具有好的综合性能,能够作为高温结构材料。 热等静压原位合成的SiC含量为3、4、5、7mol的Ti₃SiC₂/SiC复相陶瓷具有很好的致密度,相对密度都达到了98.5%以上。SiC含量为10mol的Ti₃SiC₂/SiC复相陶瓷由于在热等静压作用下Ti₃SiC₂不能形成连续的网络结构,不能完全致密化,相对密度只达到90.4%。 XRD分析结果表明:Ti₃SiC₂/SiC复相陶瓷主要存在Ti₃SiC₂、SiC相和少量的TiC相。显微硬度和断裂韧性的测量结果表明:复相陶瓷的显微硬度随SiC含量的增加而增大,最大为14.1GPa。断裂韧性随SiC含量的增加而减小,最高为7.24MPa.m^1/2。导电性能测试结果表明:随SiC含量的增加导电率降低,试验得到的电阻率与理论计算结果吻合。 Ti₃SiC₂/SiC复相陶瓷的摩擦磨损性能的测试在环块式试验机上进行,比较研究了在不同配副,不同载荷,不同润滑状态下的摩擦磨损行为,并对比了不同SiC含量的复相陶瓷/45号钢摩擦副在300N载荷,干摩擦条件下和500N载荷,油润滑条件下的摩擦磨损行为。Ti₃SiC₂/SiC复相陶瓷在干摩擦条件下摩擦系数较小,磨损率高。在油润滑条件下摩擦系数和磨损率都非常小。复相陶瓷的磨损主要是由于微断裂引起的。 研究了Ti₃SiC₂/SiC复相陶瓷在不同温度,不同气氛下的氧化行为,并结合了高温原位观察和XRD,分析了复相陶瓷的氧化机理,得出:复相陶瓷的更多还原

【Abstract】 In this paper, Ti₃SiC₂/SiC multiphase ceramics containing different contents of SiC are fabricated with TiH₂, SiC and graphite powders by in situ synthesis under hot isostatic pressing （HIP） and transient plastic phase processing（TPPP） to provide new ideal for the application of Ti₃SiC₂. Phase, grain size, grain appearance and fracture mechanism of Ti₃SiC₂/SiC composites are investigated by X-ray diffraction, optical microscope. The performances of Ti₃SiC₂/SiC composites by in situ synthesis under hot isostatic pressing （HIP） was studied via the test results on their densities, micro-hardness, fracture toughness, properties of friction and wear, and the resistance of oxidation. The research indicates that Ti₃SiC₂/SiC composites has good overall performance for high temperature structural material.Ti₃SiC₂/SiC composite samples consisting of 3,4,5,7mol SiC are full dense and the relative densities are beyond 98.5%. Ti₃SiC₂/SiC composites under HIP consisting of 10 mol SiC, In this way, Ti₃SiC₂ can not form successive net shape and be fully compact. So the relative density of sample consisting 10mol SiC only reaches 90.4%.The XRD results indicate that the major phases of Ti₃SiC₂/SiC composites are Ti₃SiC₂ and SiC, and a few TiC phases. Basically, it accords with the results designed. The results measured for micro-hardness and fracture toughness have been demonstrated that the micro-hardness of composites ceramics increases along with contents of SiC and maximum is 14.1GPa. Comparably, the fracture toughness decreases with increasing SiC and maximum is 7.24 MPam^1/2. The conductivity of composites decreases with increasing of SiC. It is identical with result of theoretical calculation.The tests of friction and wear properties of Ti₃SiC₂/SiC composites werecarried out using block-on-ring type testes to comparably research the friction and wear behaviors in different pairs, loads, and lubrication conditions. The friction coefficient of TljSiC^SiC composites is relatively low and wear rate is quite high during dry sliding, On the other hand, low friction coefficient and wear rate during lubricated sliding. The wear mechanism is considerably caused by micro-fracture.The oxidation behaviors of TisSiC^SiC composites with different temperatures and atmospheres have been discussed. Furthermore, the oxidation mechanism of TiaSiC^SiC composites was analyzed with in situ observation at high temperature and XRD. It is concluded that the high temperature oxidation dynamics curve of multiphase ceramics obeyed a parabolic law from 800 "C to 1400 °C .While temperature rising, the oxidation parabolic rate constantly increased. In the different atmospheres, oxidation could be related with oxide pressure. In the same case, oxidation mass gain rises with increasing the oxide pressure. Comparing the oxidation behaviors of TiaSiC^SiC composites with different SiC at 1200 °C, the growth of the oxide scale on TbSiC^SiC composites per area decreases with increasing in the contents of SiC. It is demonstrated that the oxidation resistance property of all Ti3SiC2/SiC composites is better than that of pure Ti3SiC2. The calculated activation energies of 7SiC and 3SiC composites are 2O8.129KJ.mor1 and 219.5 KJ.mol"1 respectively, and less than activation energy of pure Ti3SiC2. The oxide scale composed of TiO2, SiO2 grains and amorphous SiO2 can hinder the diffusion process, and results in good oxidation resistance.更多还原