發(fā)布時(shí)間：2018-03-22 01:06

  本文選題：復(fù)合膜層　切入點(diǎn)：發(fā)射率　出處：《哈爾濱工業(yè)大學(xué)》2011年碩士論文　論文類型：學(xué)位論文

【摘要】：當(dāng)飛行器在大氣中作超音速飛行時(shí),由于氣體粘性作用,其外表面高速氣流會(huì)受到壓縮和摩擦而形成氣動(dòng)加熱,在飛行器表面產(chǎn)生高溫和溫度梯度,高溫不斷由飛行器外表面向結(jié)構(gòu)內(nèi)部傳遞,從而導(dǎo)致飛行器外形及結(jié)構(gòu)強(qiáng)度和剛度的改變,并產(chǎn)生熱應(yīng)變還會(huì)產(chǎn)生材料燒蝕等現(xiàn)象,對(duì)飛行器的正常飛行造成嚴(yán)重影響。同時(shí)所產(chǎn)生的熱量向飛行器內(nèi)部傳送,引起飛行器內(nèi)部溫度升高,造成內(nèi)部工作環(huán)境惡化。本論文通過在鈦合金表面用微弧氧化法與溶膠凝膠法制成高發(fā)射率涂層提高鈦合金的高溫抗氧化性能并使飛行器表面蒙皮的熱量通過輻射傳熱的方式及時(shí)發(fā)散,使飛行器表面溫度降低。 以Na_3P_O4為電解液體系的主鹽,選擇鈦合金TC4為基體,電源輸出電壓為460V,脈沖頻率60HZ,占空比45%,氧化時(shí)間15min,通過在7g/L-16g/L范圍內(nèi)改變電解液Na_3PO_4的濃度來制備了微弧氧化陶瓷膜層厚度在5-20μm范圍內(nèi)可控的陶瓷膜層樣片。通過XRD測(cè)試分析發(fā)現(xiàn)經(jīng)過700℃煅燒之后,陶瓷膜層中除了銳鈦礦TiO2相,又產(chǎn)生了少量的金紅石TiO_2相。對(duì)陶瓷膜層進(jìn)行剪切強(qiáng)度測(cè)試以及發(fā)射率測(cè)試,發(fā)現(xiàn)隨著膜層厚度的增加,剪切強(qiáng)度降低。在5-20μm范圍內(nèi)剪切強(qiáng)度都大于15MPa,滿足膜層使用條件要求。陶瓷膜層發(fā)射率隨膜層厚度變化的規(guī)律呈現(xiàn)為:先增大,增大到一定值之后,又開始減小。 采用旋涂法在陶瓷層表面涂覆溶膠凝膠膜層,再經(jīng)過700℃高溫煅燒,形成復(fù)合膜層。對(duì)不同復(fù)合膜層進(jìn)行XRD分析,相比陶瓷膜層分別多了CuO、Cr_2O_3、CoTiO_3、CaCu_3Ti_4O_(12)的物相。對(duì)復(fù)合膜層的剪切強(qiáng)度及其發(fā)射率進(jìn)行了探討,發(fā)現(xiàn)復(fù)合膜層與基體之間的結(jié)合強(qiáng)度都比較高,而且與陶瓷膜層剪切強(qiáng)度相近。復(fù)合膜層的發(fā)射率相比陶瓷膜層的發(fā)射率有了明顯的提高,其中含過渡金屬Cr的復(fù)合膜層3-8μm波段的發(fā)射率達(dá)到0.7以上,8-20μm波段的發(fā)射率達(dá)到0.9以上。
[Abstract]:When the aircraft is flying at supersonic speed in the atmosphere, the high velocity airflow on the outer surface will be compressed and rubbed to form aerodynamic heating due to the viscous effect of the gas, which will produce high temperature and temperature gradient on the surface of the aircraft. The high temperature is continuously transferred from the exterior of the aircraft to the interior of the structure, which leads to the change of the shape, strength and stiffness of the aircraft, and the thermal strain will also produce the phenomenon of material ablation, etc. It has a serious impact on the normal flight of the aircraft. At the same time, the heat generated is transmitted to the interior of the aircraft, causing the internal temperature of the aircraft to rise. In this paper, the high emissivity coating was prepared on the surface of titanium alloy by micro-arc oxidation and sol-gel method to improve the oxidation resistance of titanium alloy at high temperature and make the heat of the skin of aircraft surface pass through the radiations. The mode of heat transfer in a timely manner, Reduce the surface temperature of the aircraft. Taking Na_3P_O4 as the main salt of electrolyte system, choosing titanium alloy TC4 as matrix, The output voltage of the power supply is 460V, the pulse frequency is 60HZ, the duty cycle is 45Hz, and the oxidation time is 15min. By changing the concentration of electrolyte Na_3PO_4 in the range of 7g/L-16g/L, the ceramic film samples with the thickness of micro-arc oxidation ceramic film controlled in the range of 5-20 渭 m have been prepared by XRD. The test results show that after calcination at 700 鈩，

本文編號(hào)：1646358