【摘要】：耐高溫材料已經(jīng)成為近幾年的科研熱點,其中ZrB_2因其優(yōu)異的物理化學(xué)性質(zhì)而逐漸成為了研究重點。上世紀60年代ZrB_2的制備工藝就已經(jīng)相當成熟,但是ZrB_2具有的穩(wěn)定共價鍵使其難以燒結(jié),在空氣中容易氧化等缺點已經(jīng)成為其應(yīng)用的障礙。本文在對ZrB_2充分的調(diào)研基礎(chǔ)上,分別對微米級ZrB_2粉體的制備、無壓燒結(jié)和SPS燒結(jié)對材料致密度的影響進行了分析和探究。為了得到抗氧化性能較好的ZrB_2復(fù)合材料,本文利用SPS燒結(jié)所得的塊體ZrB_2-SiC的三層氧化結(jié)構(gòu)對材料抗氧化性能的提高進行了研究,以及ZrB_2-SiC塊體復(fù)合材料的電學(xué)性能基礎(chǔ)進行了分析和探究。本文研究了溶膠-凝膠工藝對于制備ZrB_2粉體的影響,利用溶膠-凝膠法制備得到前驅(qū)體粉末,研磨干燥后在1550℃的高溫下煅燒得到ZrB_2粉體,在四種不同原料配比中選擇了適合實驗條件的配比。研究發(fā)現(xiàn),在蔗糖2.5 g,正丙醇鋯5.3 g,硼酸2.97 g的原料分配下得到了較為純凈的Zr B2粉體,制備得到的Zr B2為10-20μm大小的棒狀顆粒;煅燒的保溫時長有助于顆粒的不規(guī)則生長。本文重點研究了ZrB_2的氧化特性,首先對ZrB_2顆粒和塊體在空氣中的氧化溫度做了定量分析,實驗表明顆粒和塊體都在600-700℃時氧化,塊體在1000℃以下為鈍化氧化,有著阻礙氧化的作用。同時在研究了其燒結(jié)性能的基礎(chǔ)上,利用燒結(jié)致密度相對較高的ZrB_2-10mol%SiC進行了抗氧化研究,ZrB_2-10mol%SiC材料隨著氧化溫度的不斷升高,在材料的表面會有一層ZrO2來隔離其與空氣的聯(lián)系,能夠防止材料內(nèi)部的繼續(xù)氧化;在低溫氧化的過程中,氧化時長對于氧化的影響并不明顯。ZrB_2-10mol%SiC材料在高溫氧化中,由于B2O3的揮發(fā)性將會形成三層的塊狀結(jié)構(gòu),第一層為SiO2和ZrO2的保護層,第二層為SiO2和ZrO2以及ZrB_2-SiC的混合層以及第三層的ZrB_2-SiC材料層。同時利用SPS燒結(jié)所得的ZrB_2樣品,研究了ZrB_2材料的電學(xué)特性,實驗表明,ZrB_2在室溫下的電阻率為8.062μΩ·cm;ZrB_2-SiC復(fù)合材料的電阻率與SiC的加入量成正比的關(guān)系,室溫下,ZrB_2-10mol%SiC、ZrB_2-20mol%SiC、ZrB_2-30mol%SiC的電阻率分別為:9.836μΩ·cm、13.987μΩ·cm、15.124μΩ·cm。
[Abstract]:High temperature resistant materials have become a hot research topic in recent years, among which ZrB_2 has gradually become the focus of research because of its excellent physical and chemical properties. In the 1960s, the preparation process of ZrB_2 has been quite mature, but the stable covalent bond of ZrB_2 makes it difficult to sintering, and its easy oxidation in air has become an obstacle to its application. In this paper, based on the full investigation of ZrB_2, the preparation of micron ZrB_2 powder, the effect of pressuresless sintering and SPS sintering on the density of the material were analyzed and investigated. In order to obtain ZrB_2 composites with good oxidation resistance, the improvement of oxidation resistance of bulk ZrB_2-SiC sintered by SPS was studied in this paper, and the electrical properties of ZrB_2-SiC bulk composites were analyzed and investigated. In this paper, the effect of sol-gel process on the preparation of ZrB_2 powder was studied. The precursor powder was prepared by sol-gel method. The ZrB_2 powder was calcined at 1550 鈩，

本文編號：2511410