【作者】 赵旭；

【导师】 乔英杰；

【作者基本信息】 哈尔滨工程大学 ， 材料科学与工程， 2015， 硕士

【摘要】 碳化硅陶瓷具有强度高、硬度大,耐磨性好等特点,得以被广泛应用。但SiC陶瓷的室温脆性大,制约其在高端领域的应用,如何提高SiC陶瓷的韧性,是陶瓷界学者始终关心的问题,传统增韧方法多集中在相变增韧,纳米改性等方面研究,对SiC陶瓷韧性的提高起到积极的作用。为进一步改善SiC陶瓷的韧性,本项研究开展MoSi₂与SiC陶瓷复合增韧,SiC陶瓷流延层状增韧的研究。通过研究制备出可用于层状SiC陶瓷制备用的流延生带,确定流延生带制备工艺,揭示影响流延生带性能因素。因此,本项研究对SiC陶瓷的增韧,具有重要的意义和工程应用价值。MoSi₂金属间化合物具有良好的韧性和耐高温性能,将Mo Si₂金属间化合物SiC陶瓷复合可以改善SiC陶瓷的韧性。因此,本研究提出将MoSi₂与SiC制备SiC-MoSi₂复合陶瓷的思想,以期改善SiC陶瓷的韧性。本文基于生物学层状增韧理论,设计层状SiC陶瓷及层状SiC-MoSi₂复合陶瓷,重点开展SiC及SiC-MoSi₂流延生带制备研究。研究中以乙醇为溶剂、PVB为粘结剂、DBP为增塑剂、蓖麻油为分散剂,通过流延工艺制备了SiC及SiC-MoSi₂陶瓷流延浆料和生带,研究了蓖麻油用量和球磨时间对粉体的分散性的影响,分析了固相含量、PVB和DBP含量及MoSi₂在复合粉体中的含量对浆料流变性质、生带拉伸强度和断裂伸长率的影响,并且通过对生带进行热重分析制定了合理的排胶制度。研究结果表明,最佳SiC流延浆料的组成工艺为,在9.0 wt%的PVB-乙醇胶黏剂中加入PVB-乙醇胶黏剂质量的106%的SiC粉体,0.8%的蓖麻油分散剂和7%的DBP增塑剂。在球磨机转速为180 rpm,粉体与磨球质量比为1:1,大小球比1:2,球磨5 h的工艺条件下,制备的SiC流延浆料粘度最低,流延性最好。随着流延浆料中PVB-乙醇胶黏剂浓度的增加,制备的流延生带拉伸强度增大。随着流延浆料SiC粉体添量的增加,制备的流延生带断裂伸长率减小。在50g浓度为9.0 wt%的PVB-乙醇胶黏剂中加入53g SiC粉体,3.5g的DBP制备的SiC流延生带拉伸强度最大为0.74 MPa,断裂伸长率为38.4%。MoSi₂添加在SiC中可以改善SiC浆料的流延性能。当MoSi₂掺量为10 wt%时,SiC-MoSi₂复合陶瓷流延浆料的流延性能最好,制备的SiC-MoSi₂流延生带拉伸强度最大为0.86 MPa,断裂伸长率达71.2%。制定生带排胶升温速率为5℃/min,并在有机物剧烈分解温度区间进行保温处理。更多还原

【Abstract】 Silicon carbide（SiC）is widely used in many fields because of its high strength,high hardness,good abrasion resistance,etc.But SiC is brittle at room temperature,which restricts its application in the high-end field.How to improve the brittleness of SiC is a center task in ceramic research field.Traditional toughening methods focus on the phase transformation toughening,nanometer modification toughening etc.This research investigated the toughening of SiC-MoSi₂ composite and laminated SiC by tape casting.The SiC green tapes and its preparation technology was prepared and researched,respectively,which had important significance and engineering application value.MoSi₂ intermetallic compound has good toughness and high temperature resistant performance,which can be used in improving the toughness of SiC by preparing SiC-MoSi₂ composite.This research designed the laminated SiC and laminated Si C-MoSi₂ composite,based on the theory of biological layered toughening.The preparation technology of SiC and SiC-MoSi₂ composite green tapes by tape casting was mainly investigated.In this paper,SiC slurry and SiC-MoSi₂ composite slurry for tape casting were prepared with ethanol,PVB and DBP as the solvent,the binder and the plasticizer,respectively.Then the slurry was prepared to green tapes by tape casting.In this process,the effect of dispersant amount and milling time on powder dispersion,content of powder,PVB and DBP,the quality ratio of MoSi₂/SiC-MoSi₂ on rheological property of slurry,tensile strength and breaking elongation of tapes were investigated in detail.The height of doctor blade gap on the thickness of green tapes was investigated.The reason that performance differences in different directions of green tapes was analyzed.The debinding of green tapes was researched by TG as well.The slurry with low viscosity and excellent rheological properties could be prepared when the concentration of PVB-ethanol adhesive was 9.0 wt%,the quality of SiC powder,castor oil dispersant and DBP plasticizer were 106%,0.8%and 7%of the adhesive quality respectively.The making process was established:rotation speed was 180 rpm,quality ratio of powder/ball was 1:1,quality ratio of large ball/small ball was 1:2,the time of ball milling was 5h.The tensile strength of green tapes increased with the rising of the PVB-ethanol adhesive concentration.The breaking elongation of green tapes decreased with the increase of the Si C quality.The tensile strength of SiC green tapes reached 0.74 MPa,and the breaking elongation was 38.4%.When MoSi₂ was added to replace a part of SiC,the rheological property of SiC-MoSi₂ was improved.SiC-MoSi₂ composites slurry had proper rheological property,when the mass fraction of MoSi₂ reached 10 wt%.SiC-10wt%Mo Si₂ had the highest mechanical properties--the tensile strength and breaking elongation 0.74 MPa,and the breaking elongation was 38.4%.The heating rate was chosen 5℃/min when the binder in green tapes was removed by heating,and for making sure polymers were burning out completely,insulation measures were taken when the organic components were broken down acutely.更多还原