本文選題：碳納米蔥　切入點(diǎn)：立方氮化硼　出處：《燕山大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：金剛石是世界上硬度最高的材料,并且具有極高的熱導(dǎo)系數(shù),但由于金剛石的熱穩(wěn)定性差,金剛石工具在高溫環(huán)境下工作會(huì)發(fā)生嚴(yán)重的熱磨損。聚晶立方氮化硼熱穩(wěn)定性較好,并且是公認(rèn)的切削黑色金屬和高硬度碳化物的最好材料,而金剛石工具卻完全不能加工上述材料,但聚晶立方氮化硼的維氏硬度較低,僅為33~45 GPa。本論文首次將碳納米蔥(OLC)與立方氮化硼(cBN)混合后在高溫高壓條件下燒結(jié),旨在研究一種金剛石和立方氮化硼的復(fù)合材料,使其耐熱性、耐磨性,硬度和斷裂韌性等物理性能更加優(yōu)異,研究cBN的添加量、燒結(jié)條件和cBN顆粒表面狀態(tài)對(duì)OLC-cBN燒結(jié)體組織和性能的影響。對(duì)燒結(jié)樣品進(jìn)行XRD、FESEM、HRTEM和維氏硬度分析,最終得出,燒結(jié)效果較為理想的工藝條件是加入30wt.%的cBN,燒結(jié)壓力為6 GPa,溫度為1300℃,保溫時(shí)間為15 min,此時(shí)OLC-cBN燒結(jié)體硬度為36.66 GPa,OLC向金剛石的轉(zhuǎn)化率為46.66%,合成的聚晶金剛石和添加的cBN顆粒間結(jié)合的非常緊密。本論文將OLC與多壁碳納米管(MWCNT)混合后在高溫高壓下燒結(jié),旨在通過(guò)這種方法降低OLC向金剛石轉(zhuǎn)變的溫度、提高OLC轉(zhuǎn)化率,并且優(yōu)化混合燒結(jié)體的性能,研究燒結(jié)條件對(duì)OLC-MWCNT燒結(jié)體的組織和性能的影響,最終得出,加入MWCNT質(zhì)量分?jǐn)?shù)為10%時(shí),最佳工藝條件為:燒結(jié)壓力5.5 GPa,溫度1150℃,保溫時(shí)間20 min,該條件下,燒結(jié)體硬度為18.84 GPa,OLC向金剛石的轉(zhuǎn)化率為25.96%。
[Abstract]:Diamond is the highest hardness material in the world, and it has very high thermal conductivity. However, due to the poor thermal stability of diamond, diamond tools will suffer serious thermal wear in high temperature environment, and polycrystalline cubic boron nitride has good thermal stability. And is recognized as the best material for cutting ferrous metals and high-hardness carbides, but diamond tools can't process them at all, but polycrystalline cubic boron nitride has lower Vickers hardness. In this paper, the carbon nano-scallion (OLC) and cubic boron nitride (cBN) were mixed for the first time and sintered under high temperature and high pressure. The purpose of this paper is to study a kind of diamond and cubic boron nitride composite material, which can make it heat-resistant and wear-resistant. The physical properties such as hardness and fracture toughness are more excellent. The effects of the addition of cBN, sintering conditions and the surface state of cBN particles on the microstructure and properties of OLC-cBN sintered body are studied. The optimum sintering conditions are as follows: adding 30 wt.% cBN, sintering pressure 6 GPA, temperature 1300 鈩，

本文編號(hào)：1630797