【摘要】：作為性能優(yōu)異的高溫結(jié)構(gòu)材料,碳化硅陶瓷已廣泛地應(yīng)用于石油化工、航空航天、機(jī)械密封、電子封裝等領(lǐng)域,因此,開展碳化硅陶瓷的力學(xué)及熱學(xué)性能的研究具有十分重要的意義。無壓液相燒結(jié)由于工藝簡單、燒結(jié)溫度低、制品的力學(xué)性能優(yōu)異,已成為一種很有發(fā)展前途的燒結(jié)技術(shù)。而燒結(jié)助劑的合理選擇是該技術(shù)中的重要研究內(nèi)容。本論文以α-SiC與β-SiC為主要原料,分別引入La_2O_3-Y_2O_3、AlN-Y_2O_3-MgO和AlN-Y_2O_3-La_2O_3-MgO三種助燒劑,采用無壓液相燒結(jié)工藝制備了6個體系的30個碳化硅陶瓷樣品,并對其物相、表面形貌、密度、力學(xué)及熱學(xué)性能進(jìn)行了測量與分析。1)SiC-La_2O_3-Y_2O_3系列陶瓷的研究結(jié)果表明:隨著燒結(jié)助劑含量的增加,不同配比α-SiC-La_2O_3-Y_2O_3陶瓷的密度、相對密度、硬度、熱導(dǎo)率呈現(xiàn)完全相同的變化趨勢,熱膨脹系數(shù)則呈現(xiàn)單邊上升趨勢;而不同配比β-SiC-La_2O_3-Y_2O_3陶瓷的的密度、相對密度及硬度呈現(xiàn)先增加后減小的變化規(guī)律,熱膨脹系數(shù)則呈現(xiàn)先減小后增加的變化趨勢;在所有10個樣品中,燒結(jié)助劑為9wt.%的α-SiC-La_2O_3-Y_2O_3陶瓷的各項性能均最優(yōu),它的密度、相對密度、硬度分別為3.1169g/cm3、93.13%、1021.000kgf/mm2,熱導(dǎo)率為112.495W/(m·K),熱膨脹系數(shù)為0.3181×10-6/K。2)SiC-AlN-Y_2O_3-Mg O陶瓷的研究結(jié)果表明:燒結(jié)助劑含量的變化,對SiC-AlN-Y_2O_3-MgO陶瓷的密度、硬度、熱導(dǎo)率、熱膨脹系數(shù)都產(chǎn)生了明顯的影響,相同配比的β-SiC-AlN-Y_2O_3-MgO和α-SiC-AlN-Y_2O_3-MgO陶瓷的密度和硬度相比,后者總是優(yōu)于前者,而熱導(dǎo)率和熱膨脹系數(shù)的變化比較復(fù)雜;在相應(yīng)的10個樣品中,燒結(jié)助劑含量為19.5wt.%α-SiC-AlN-Y_2O_3-MgO陶瓷的密度、相對密度及硬度最大,分別為3.3481g/cm3,98.8%;助劑含量為22wt.%α-SiC-AlN-Y_2O_3-MgO陶瓷硬度最大,為1929.933kgf/mm2;助劑含量為17%的β-SiC-AlN-Y_2O_3-MgO熱膨脹系數(shù)最小為1.51×10-6/K;22wt.%的β-SiC-AlN-Y_2O_3-MgO陶瓷熱導(dǎo)率最大,為103.367W/(m·K)。3)SiC-AlN-Y_2O_3-La_2O_3-Mg O陶瓷的研究結(jié)果表明:燒結(jié)助劑含量為17%的α-SiC-AlN-Y_2O_3-La_2O_3-MgO和β-SiC-AlN-Y_2O_3-La_2O_3-MgO陶瓷的密度、相對密度、硬度均為最大,密度分別為3.1764g/cm3,3.0555g/cm3,相對密度分別為92.16%,86.76%,硬度分別為1753.800kgf/mm2,2323.433kgf/mm2;助劑含量為12wt.%時α-SiC-AlN-Y_2O_3-La_2O_3-MgO與β-SiC-AlN-Y_2O_3-La_2O_3-MgO兩組陶瓷體系的熱膨脹系數(shù)有最小值,分別為1.4554×10-6/K、0.2220×10-6/K;助劑含量為14.5wt.%時α-SiC-AlN-Y_2O_3-La_2O_3-Mg O陶瓷體的導(dǎo)熱率最大,在50℃下,其熱導(dǎo)率為69.479W/(m·K),助劑含量為22.0wt.%時β-SiC-AlN-Y_2O_3-La_2O_3-MgO陶瓷的導(dǎo)熱率最大,在50℃時,其導(dǎo)熱率可達(dá)63.396W/(m·K)。
[Abstract]:As a high temperature structure material with excellent performance, silicon carbide ceramics have been widely used in petrochemical, aerospace, mechanical sealing, electronic packaging and other fields. It is of great significance to study the mechanical and thermal properties of sic ceramics. Due to its simple process, low sintering temperature and excellent mechanical properties, pressureless liquid sintering has become a promising sintering technology. The reasonable selection of sintering additives is an important research content in this technology. In this paper, 偽-SiC and 尾-SiC were used as main raw materials, and La_2O_3-Y_2O_3,AlN-Y_2O_3-MgO and AlN-Y_2O_3-La_2O_3-MgO were introduced respectively. 30 silicon carbide ceramic samples were prepared by pressureless liquid phase sintering process, and their phase, surface morphology and density were analyzed. The mechanical and thermal properties were measured and analyzed. 1) the research results of SiC-La_2O_3-Y_2O_3 series ceramics show that: with the increase of the content of sintering auxiliaries, The density, relative density, hardness and thermal conductivity of 偽-SiC-La_2O_3-Y_2O_3 ceramics with different ratios showed the same change trend, while the thermal expansion coefficient showed a unilateral upward trend. The density, relative density and hardness of 尾-SiC-La_2O_3-Y_2O_3 ceramics with different ratios increased first and then decreased, while the coefficient of thermal expansion decreased first and then increased. Among all the 10 samples, the 偽-SiC-La_2O_3-Y_2O_3 ceramics with 9 wt.% sintering aids have the best properties. Its density, relative density and hardness are 3.1169 g / cm ~ (3 93) ~ (13) and 1021.000 kg / m ~ (2) / m ~ (-2), respectively. The study on the thermal conductivity of 0.3181 脳 10-6/K.2 SiC-AlN-Y_2O_3-Mg O ceramics with 112.495W/ (m K), thermal expansion coefficient shows that the content of sintering aids varies. The density, hardness, thermal conductivity and thermal expansion coefficient of SiC-AlN-Y_2O_3-MgO ceramics are obviously affected. Comparing the density and hardness of 尾-SiC-AlN-Y_2O_3-MgO and 偽-SiC-AlN-Y_2O_3-MgO ceramics with the same ratio, the latter is always better than the former, while the variation of thermal conductivity and thermal expansion coefficient is more complex. The density, relative density and hardness of 偽-SiC-AlN-Y_2O_3-MgO ceramics containing 19.5 wt.% 偽-SiC-AlN-Y_2O_3-MgO were the highest, which were 3.3481g / cm ~ 398.8, respectively. The hardness of 22wt.% 偽-SiC-AlN-Y_2O_3-MgO ceramics was the highest (1929.933kg / m ~ (-2) and the thermal expansion coefficient of 尾-SiC-AlN-Y_2O_3-MgO with 17% additive content was 1.51 脳 10 ~ (-6) / kg 路m ~ (-2) 路L ~ (-1) 路min ~ (-1). 22wt.% 尾-SiC-AlN-Y_2O_3-MgO ceramics have the highest thermal conductivity. The results of study on SiC-AlN-Y_2O_3-La_2O_3-Mg O ceramics with 103.367W/ (m K). 3 show that 偽-SiC-AlN-Y_2O_3-La_2O_3-MgO with a content of 17% of sintering aids is obtained. And the density of 尾-SiC-AlN-Y_2O_3-La_2O_3-MgO ceramics, The relative density and hardness were 3.1764g / cm ~ (-3) and 3.0555g / cm ~ (-3), respectively. The relative densities were 92.16kg / cm ~ (-2) and 86.76%, respectively, and the hardness were 1753.800 kg / m ~ (-2) and 2323.433 kg / m ~ (2) respectively. The thermal expansion coefficient of 偽-SiC-AlN-Y_2O_3-La_2O_3-MgO and 尾-SiC-AlN-Y_2O_3-La_2O_3-MgO ceramic systems is minimum when the additive content is 12 wt.%, which is 1.4554 脳 10 ~ (-6) / K, respectively. 0.2220 脳 10 ~ (-6) / K; The thermal conductivity of 偽-SiC-AlN-Y_2O_3-La_2O_3-Mg O ceramics is the highest when the additive content is 14.5 wt.%, and the thermal conductivity is 69.479W/ (m K), at 50 鈩，

本文編號：2358518