sic陶瓷的高压烧结工艺及性能论文.doc

SiC陶瓷的高压烧结工艺及性能材料专业本科毕业论文河

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摘要
碳化硅陶瓷具有高温强度高、抗氧化性强、耐磨损性好、热膨胀系数小、硬度高、抗热震和耐化学腐蚀等优良特性,因此,在很多领域得到广泛应用。然而,SiC是一种共价键性很强的化合物,其自扩散系数极小,可烧结性很差。在传统的粉末冶金SiC烧结工艺条件下,如果不加入适当的添加剂,纯SiC是很难烧结致密化。采用超高压烧结方法可以在较低温度、较短时间、低烧结助剂添加量下获得高致密度、高性能的陶瓷。
本文利用高压六面顶压机对SiC陶瓷的高压烧结，对SiC陶瓷的高压烧结工艺及性能进行了初步的研究，并进行了理论分析，探索了其显微结构与性能之间的关系。通过对SiC复相陶瓷的相对密度和XRD谱的研究分析，发现高压烧结的SiC陶瓷材料具有优良的性能，主要体现在导热性能和韧性在，有良好的应用前景。
与常压相比，高压烧结可以有效的降低金属陶瓷的烧结时间和烧结制度，增进致密化，进而达到改进性能的目的。六面顶高压烧结技术是一种快速、高效的烧结技术，大大降低了烧结温度和缩短了烧结时间，并且可制备出接近理论密度的复相陶瓷材料。采用超高压烧结工艺可以烧结获得无烧结助剂添加的高致密度SiC陶瓷(致密度92%~100%)。烧结工艺对陶瓷的性能有明显的影响，实验结果表明：Al2O3是SiC烧结的有效烧结助剂,在低添加量下(约2wt%)即可实现陶瓷的全致密烧结。烧结工艺对添加了烧结助剂陶瓷性能的影响与纯SiC的烧结类似,但获得的陶瓷的致密度普遍较高。

关键词：SiC陶瓷高温高压技术烧结性能物相分析（XRD谱)

ABSTRACT
SiCceramicsisagoodmaterialwithhightemperaturestrength,oxidationresistance,wearresistance,thermalexpansioncoefficient,highhardness,thermalshockandchemicalresistanceandotherexcellentproperties,therefore,hasbeenwidelyusedinmanyfields.However,SiCisacovalentbondstrongcompound,theself-diffusioncoefficientisextremelysmall,thesinterabilityispoor.SiCsinteredintheconventionalpowdermetallurgyprocessconditions,withouttheinclusionofsuitableadditives,pureSiCdensificationisdifficult.Usingultra-highpressuresinteringmethodcanlowerthetemperature,theshorterthetime,thelowsinteringadditivesaddedamountobtainedbyahigh-densityandhigh-performanceceramic.
Inthispaper,basedonsixsideshigh-pressurejackingmachineofSiCceramicshighpressuresintering,highpressuresinteringprocessandtheperformanceofSiCceramicshascarriedonthepreliminaryresearch,andhascarriedonthetheoreticalanalysis,toexploretherelationshipbetweenitsmicrostructureandproperties.ThroughtherelativedensityofSiCceramiccompoundphasespectrumandXRDanalysis,foundthathighpressuresinteringSiCceramicmaterialwithexcellentperformance,mainlyreflectedintheperformanceofthermalconductivityandtoughnessin,hasthegoodapplicationprospect.
Comparedwithnormalpressure,highpressuresinteringcaneffectivelyreducemetalsinteringtimeandsinteringtheceramicsystem,promotedens