本文選題：鐵族金屬　切入點(diǎn)：金剛石單晶　出處：《湖南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：金剛石因具有高硬度、高強(qiáng)度、高耐磨性以及高導(dǎo)熱性等一系列優(yōu)點(diǎn)而在許多領(lǐng)域得到廣泛應(yīng)用。但以共價(jià)鍵結(jié)合的金剛石具有較高的表面能,且人造金剛石單晶表面非常光滑,導(dǎo)致其在磨具中與結(jié)合劑之間的結(jié)合力較弱,縮短磨具的使用壽命。本文首次采用鐵族金屬高溫催化腐蝕法對金剛石單晶進(jìn)行表面處理,在金剛石表面形成腐蝕凹坑,增加金剛石的表面粗糙度,從而提高磨具中結(jié)合劑對其的把持力。論文主要研究內(nèi)容及成果如下:1、分別以Fe、Co、Ni作為催化腐蝕劑,研究不同處理溫度和保溫時(shí)間對金剛石單晶表面腐蝕的微觀形貌和腐蝕深度的影響。結(jié)果表明:在鐵族金屬的催化作用下,金剛石表面的腐蝕深度隨著溫度的升高、保溫時(shí)間的延長而增加,與延長保溫時(shí)間相比,升高處理溫度對促進(jìn)金剛石的腐蝕更有效。2、在相同腐蝕工藝條件下,金剛石的{100}面均比{111}面更容易被腐蝕,在{100}面傾向于形成倒立的金字塔狀腐蝕坑,而在{111}面易于形成底部平坦光滑、外部輪廓為三角形或六邊形的腐蝕坑,且腐蝕后金剛石單晶整體還保留了原來的顆粒形貌;拉曼光譜的分析結(jié)果表明,腐蝕坑的形成是金剛石的石墨化所致。3、腐蝕后金剛石的基本結(jié)構(gòu)得到了保留,其強(qiáng)度隨著處理溫度的升高而略有降低。與未處理的金剛石單晶相比,960℃時(shí),經(jīng)Fe催化腐蝕后金剛石的TI值和TTI值分別降低3.17%和1.88%;930℃時(shí),經(jīng)Co催化腐蝕后金剛石的TI值和TTI值分別降低3.96%和2.18%,單顆粒抗壓強(qiáng)度僅下降了5.6%。4、在實(shí)驗(yàn)條件下,采用Co腐蝕金剛石所需的處理溫度最低,采用Fe腐蝕所需的溫度最高;在870℃條件下,經(jīng)Fe處理后的金剛石{100}面和{111}面的腐蝕率分別為0.939%、0.785%,在810℃條件下,經(jīng)Co和Ni處理后的金剛石{100}面的腐蝕率分別為51.631%和13.278%,{111}面的腐蝕率分別為34.062%和4.158%,結(jié)合不同條件下金剛石表面腐蝕坑的分布情況表明:相對整顆金剛石而言,經(jīng)Co處理后金剛石的表面腐蝕率最高且腐蝕均勻性最好,Ni次之,Fe最差。5、鐵族金屬催化腐蝕金剛石單晶的機(jī)理為:隨溫度的升高和保溫時(shí)間的延長,固態(tài)金屬逐漸熔融形成液相,使金屬與金剛石之間的界面接觸狀態(tài)由點(diǎn)接觸逐漸轉(zhuǎn)變成面接觸,熔融的金屬促使碳原子由金剛石相轉(zhuǎn)變?yōu)槭?并且形成的石墨相碳通過熔融金屬向遠(yuǎn)離金剛石—金屬界面的一端進(jìn)行擴(kuò)散。
[Abstract]:Diamond is widely used in many fields because of its advantages of high hardness, high strength, high wear resistance and high thermal conductivity. Moreover, the surface of synthetic diamond single crystal is very smooth, which leads to the weak bonding force between diamond and binder and shortens the service life of abrasive tool. In this paper, the surface of diamond single crystal is treated by high temperature catalytic corrosion method of iron group metal for the first time. Corrosion pits are formed on the surface of diamond to increase the surface roughness of diamond, so as to improve the holding power of binders in abrasive tools. The main contents and results of this paper are as follows: 1. The effects of different treatment temperature and holding time on the microstructure and corrosion depth of diamond single crystal surface were studied. The results show that the corrosion depth of diamond surface increases with the increase of temperature under the catalysis of iron group metal. Compared with prolonging holding time, increasing treatment temperature is more effective in promoting diamond corrosion. Under the same corrosion conditions, the {100} surface of diamond is more easily corroded than that of {111} surface. On the {100} plane, the inverted pyramidal corrosion pits tend to be formed, while on the {111} plane, the corrosion pits with flat bottom and smooth bottom and triangular or hexagonal exterior contour are easily formed, and the original morphology of the diamond single crystal remains after corrosion. The results of Raman spectra show that the formation of corrosion pits is caused by graphitization of diamond. The basic structure of etched diamond is preserved. Compared with the untreated diamond crystal at 960 鈩，

本文編號：1652504