本文選題：鈦基復(fù)合材料 + 激光熔覆技術(shù)　； 參考：《沈陽(yáng)航空航天大學(xué)》2017年碩士論文

【摘要】：鈦基復(fù)合材料(Titanium Matrix Composites,TMCs)具有比鈦合金更高的比強(qiáng)度,以及極佳的蠕變和疲勞性能,且克服了鈦合金耐磨性能差、彈性模量低等不足,在航空航天、醫(yī)療工程、化學(xué)工業(yè)等領(lǐng)域得到廣泛應(yīng)用。本文通過(guò)激光單道單層掃描實(shí)驗(yàn),探索本課題所需要的TMCs的合適激光工藝參數(shù);采用激光熔覆技術(shù),以TA15和B4C的混合粉末為原料,原位合成以TiB-TiC為增強(qiáng)相的顆粒增強(qiáng)鈦基復(fù)合材料。借助XRD、SEM、EDS和硬度測(cè)試、室溫拉伸實(shí)驗(yàn)和室溫耐磨實(shí)驗(yàn),研究本課題所制得的TMCs的組織、力學(xué)性能和耐磨性能。試驗(yàn)結(jié)果表明,激光熔覆顆粒增強(qiáng)鈦基復(fù)合材料的合適激光成形工藝參數(shù)范圍為:激光功率1600~2000W,掃描速度6~8mm/s,送粉速率7.5~9.5g/min。四種鈦基復(fù)合材料中增強(qiáng)相的大小和形態(tài)存在差異,但由XRD結(jié)果表明,四種鈦基復(fù)合材料的組織均由α-Ti、β-Ti、TiC和TiB四種相組成。鈦基復(fù)合材料增強(qiáng)相的主要形態(tài)有棱柱狀、晶須狀和近似等軸狀顆粒,且隨著B(niǎo)4C添加量的增加,原位合成的增強(qiáng)相數(shù)量增多,尺寸增大。其中,棱柱狀和晶須狀的增強(qiáng)相為Ti B,近似等軸狀增強(qiáng)相為TiC。而增強(qiáng)相的尺寸大小和形狀與其自身的晶體類型及結(jié)構(gòu)和從液相中凝固析出的過(guò)程密切相關(guān)。TiB為B27結(jié)構(gòu),易于生成晶須狀或棱柱狀。而TiC的晶體結(jié)構(gòu)為NaCl型,易于生成等軸狀的結(jié)構(gòu)。性能測(cè)試的結(jié)果表明:隨著增強(qiáng)相含量的增加,鈦基復(fù)合材料的硬度呈增高趨勢(shì),摩擦系數(shù)變化不大,磨損失重和抗拉強(qiáng)度均呈先減小后增大的趨勢(shì),延伸率呈下降趨勢(shì)。B元素和C元素含量為0.83 wt%和0.44 wt%的鈦基復(fù)合材料的抗拉強(qiáng)度最高,摩擦系數(shù)最小;而B(niǎo)元素和C元素含量為1.2wt%和0.84wt%的鈦基復(fù)合材料的磨損失重最少,與基材相比減少了47%。鈦基復(fù)合材料的斷裂方式均為準(zhǔn)解理斷裂,磨損機(jī)制均為磨粒磨損和極少量氧化磨損。
[Abstract]:Titanium Matrix composites have higher specific strength than titanium alloy, excellent creep and fatigue properties, and overcome the disadvantages of poor wear resistance and low elastic modulus of titanium alloy.Chemical industry and other fields have been widely used.In this paper, the suitable laser technological parameters of TMCs are explored by single-channel single-layer laser scanning experiment, the laser cladding technology is adopted, and the mixed powder of TA15 and B4C is used as raw material.Particle reinforced titanium matrix composites with TiB-TiC as reinforcement phase were synthesized in situ.The microstructure, mechanical properties and wear resistance of TMCs prepared in this paper were studied by means of XRDX SEM DS and hardness test, room temperature tensile test and room temperature wear resistance test.The experimental results show that the suitable laser forming parameters for laser cladding particle reinforced titanium matrix composites are as follows: laser power 1600 W, scanning speed 6 ~ 8 mm / s, powder feeding rate 7.5 ~ 9.5 g / min.The size and morphology of the reinforcing phases in the four titanium matrix composites are different, but the XRD results show that the microstructure of the four titanium matrix composites is composed of 偽 -Ti, 尾 -TiTiC and TiB phases.The reinforcing phases of titanium matrix composites are mainly prismatic, whisker and nearly equiaxed particles. With the increase of B _ 4C, the number and size of in-situ reinforced phases increase.Among them, the reinforcement phase of prism and whisker is TiB, and the similar equiaxed reinforcement is tic.The size and shape of the reinforcing phase are closely related to its crystal type and structure and the precipitation process from liquid phase. TIB is B27 structure, and it is easy to form whisker or prism.However, the crystal structure of TiC is NaCl type, and it is easy to form equiaxed structure.The results showed that the hardness of titanium matrix composites increased with the increase of reinforcing phase content, the friction coefficient changed little, and the wear weight loss and tensile strength decreased first and then increased.The tensile strength and friction coefficient of titanium matrix composites with 0.83 wt% and 0.44 wt% C elements were the highest and the friction coefficient was the lowest, while the wear weight loss of titanium matrix composites with 1.2wt% and 0.84wt% of B and C elements were the least, and the tensile strength and friction coefficient of titanium matrix composites with 0.83 wt% and 0.44 wt% of C elements were the lowest, respectively.There is a reduction of 47% compared with the base material.The fracture modes of titanium matrix composites are quasi-cleavage fracture, wear mechanism are abrasive wear and very little oxidation wear.
【學(xué)位授予單位】：沈陽(yáng)航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB333

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