本文選題：無Co硬質(zhì)合金 + 超硬顆粒　； 參考：《中國(guó)地質(zhì)大學(xué)(北京)》2016年博士論文

【摘要】：由于具有高硬度、高強(qiáng)度和優(yōu)異斷裂韌性,硬質(zhì)合金作為制備鉆頭和釬頭的工具材料在地質(zhì)工程領(lǐng)域得到廣泛應(yīng)用。但常用的WC-Co硬質(zhì)合金抗氧化/腐蝕性較差,限制其在海底、鹽堿地及其它高氧化/腐蝕環(huán)境下的使用,且鉆頭和釬頭在工程應(yīng)用中消耗巨大,而Co價(jià)格昂貴,如能減少Co的使用,對(duì)降低鉆頭價(jià)格,減少作業(yè)成本具有重要意義。所以本論文主要集中于制備適合地質(zhì)工程用高性能無Co硬質(zhì)合金。本論文以超細(xì)WC-Ni和無金屬相硬質(zhì)合金為主要研究對(duì)象,采用放電等離子或熱壓燒結(jié)技術(shù),通過將合金與超硬顆粒、高強(qiáng)晶須/纖維或納米陶瓷顆粒進(jìn)行復(fù)合來提高無Co硬質(zhì)合金的力學(xué)性能和耐磨性能。通過對(duì)所制備樣品燒結(jié)行為、微觀結(jié)構(gòu)、力學(xué)性能和磨損行為進(jìn)行分析,結(jié)果表明:(1)超硬顆粒表面鍍Ti或鍍Cu可減少其在與WC-Ni硬質(zhì)合金復(fù)合時(shí)發(fā)生的石墨化或相轉(zhuǎn)變,當(dāng)分別添加6 wt.%DiamondTi、8 wt.%DiamondCu或15 vol.%cBNTi時(shí),合金的硬度達(dá)到最大值,分別約為2000、2000和1820 HV10;當(dāng)分別添加2 wt.%DiamondTi、2 wt.%DiamondCu或5 vol.%cBNTi時(shí),合金的抗彎強(qiáng)度達(dá)到最大值,約為960、950或1500 MPa。超硬顆粒添加量較少時(shí),合金的磨損機(jī)制主要為粘結(jié)相的去除、WC晶粒的破碎拔出和超硬顆粒的磨損,但當(dāng)超硬顆粒添加量過多時(shí),切削棱斷裂和超硬顆粒剝落變得嚴(yán)重。(2)添加約0.53 wt.%SiCw可提高WC-Ni硬質(zhì)合金的強(qiáng)度和韌性,但當(dāng)SiCw添加過多時(shí),晶須團(tuán)聚嚴(yán)重;添加預(yù)氧化聚丙烯腈纖維(PANf)可原位生成碳纖維增韌WC-Ni硬質(zhì)合金,當(dāng)添加10 vol.%PANf、燒結(jié)溫度為1300℃時(shí),所制備合金具有最高的硬度和強(qiáng)度,當(dāng)添加20 vol.%PANf時(shí),合金的斷裂韌性最高,合金的磨損機(jī)制主要為粘結(jié)相去除和WC晶粒拔出。(3)添加約3-5 wt.%納米ZrC顆�？商岣遅C-Ni硬質(zhì)合金的致密性、硬度、強(qiáng)度和斷裂韌性,且此時(shí)合金磨削花崗巖時(shí)的磨損率最小,但是當(dāng)其添加量高于7 wt.%時(shí),富Zr顆粒團(tuán)聚嚴(yán)重,合金的致密性、硬度、強(qiáng)度和韌性均有所降低,合金的磨損率增加,主要磨損機(jī)制為粘結(jié)相去除和WC晶粒拔出。(4)添加適量納米AlN、La2O3或ZrC(低于5 wt.%)可提高無金屬相硬質(zhì)合金的致密性,抑制WC晶粒的粗化,提高合金的硬度和抗彎強(qiáng)度,但當(dāng)其添加量高于5 wt.%時(shí),納米顆粒團(tuán)聚嚴(yán)重,合金的致密性降低,硬度和強(qiáng)度下降;隨著納米AlN和La2O3添加的增多,合金的斷裂韌性逐漸降低,但隨著納米ZrC添加的增多,合金的斷裂韌性先增大后減小。所制備合金的磨損率隨納米顆粒添加量的增加先減小后增加,當(dāng)合金強(qiáng)度較高時(shí)(約高于1000 MPa),磨損機(jī)制主要為WC晶粒斷裂和拔出,但當(dāng)其強(qiáng)度較低時(shí)(約低于1000 MPa),磨損機(jī)制主要為切削棱斷裂和合金成塊剝落。
[Abstract]:Because of its high hardness, high strength and excellent fracture toughness, cemented carbide has been widely used in geological engineering as a tool material for the preparation of bit and bit. However, the commonly used WC-Co cemented carbides have poor oxidation resistance / corrosion, which limits their use in seabed, saline-alkali soil and other high oxidation / corrosion environments. Moreover, bits and drill bits are consumed heavily in engineering applications, while Co is expensive. If the use of Co can be reduced, it is of great significance to reduce the price of drill bit and reduce the cost of operation. Therefore, this paper mainly focuses on the preparation of high performance Co-free cemented carbides for geological engineering. In this paper, superfine WC-Ni and metal-free cemented carbides were used as the main research objects, and the alloy and superhard particles were prepared by spark plasma or hot pressing sintering. The mechanical properties and wear resistance of Co-free cemented carbides were improved by composite of high strength whisker / fiber or nano ceramic particles. The sintering behavior, microstructure, mechanical properties and wear behavior of the prepared samples were analyzed. The results show that Ti or Cu plating on the surface of the superhard particles can reduce the graphitization or phase transition of the samples when they are compounded with WC-Ni cemented carbides. The hardness of the alloy reached the maximum value of about 2000.2000 and 1820 HV10when the alloy was added for 6 wt.DiamondTiO8 wt.%DiamondCu or 15 vol.NTi, respectively, and the flexural strength of the alloy reached the maximum value of 960950 or 1500 MPa when the alloy was added with 2 wt.DiamondTiO2 wt.%DiamondCu or 5 vol.NTi, respectively. When the content of superhard particles is small, the wear mechanism of the alloy mainly consists of the removal of bonding phase and the crushing and pull-out of WC grains and the wear of superhard particles, but when the amount of superhard particles is too much, The strength and toughness of WC-Ni cemented carbides can be improved by adding about 0.53 wt.%SiCw to the cutting edge fracture and the spalling of superhard particles, but the agglomeration of whiskers is serious when the addition of SiCw is too much. The WC-Ni cemented carbide toughened by carbon fiber can be in-situ formed by adding preoxidized polyacrylonitrile fiber (PANF). The highest hardness and strength of the alloy are obtained when the sintering temperature is 1300 鈩，

本文編號(hào)：1790098