本文選題：碳/碳復(fù)合材料 + 硅基陶瓷涂層��； 參考：《西北工業(yè)大學(xué)》2015年博士論文

【摘要】：氧化敏感性是碳/碳(C/C)復(fù)合材料高溫應(yīng)用的瓶頸,盡管硅基陶瓷涂層在1500-1600℃溫度范圍內(nèi)具有較佳的抗氧化效果,但是其較窄的防御溫度范圍以及超高溫長時間使用時易產(chǎn)生孔洞和氣泡等缺陷,極大限制了其對C/C復(fù)合材料的氧化防護(hù)壽命。將具有優(yōu)異熱物理化學(xué)特性的超高溫陶瓷硼化物相引入硅基陶瓷涂層中對其進(jìn)行改性,有希望提高硅基陶瓷涂層的性能。本文以硼化物改性硅基超高溫陶瓷涂層為研究對象,選用原位反應(yīng)法制備了ZrB2、TaB2、HfB2、(Zr,Ta)B2和(Ta,Hf)B2改性硅基涂層,考察了其在1773 K靜態(tài)空氣氧化環(huán)境、室溫-1773 K動態(tài)氧化環(huán)境,熱流為2400KW/m2的氧乙炔焰嚴(yán)苛高溫?zé)g測試環(huán)境和1873K風(fēng)洞燃?xì)鉀_刷環(huán)境下的氧化防護(hù)能力,通過XRD、SEM和EDS等測試手段,對試樣氧化測試前后的物相、形貌和元素組成等進(jìn)行了分析,研究了硼化物改性對硅基超高溫陶瓷涂層微觀結(jié)構(gòu)與防護(hù)性能的影響,并探討其氧化失效機(jī)理,主要內(nèi)容和結(jié)果如下:選取過渡族金屬氧化物MxOy(MxOy=ZrO2、Ta2O5和HfO2)作為超高溫陶瓷硼化物MB2中過渡族金屬M(fèi)的源材料,B2O3粉作為B源,C粉用作碳源,硅粉作為Si源,采用原位反應(yīng)法,經(jīng)過高溫?zé)崽幚?通過碳熱還原反應(yīng)與固相反應(yīng)相結(jié)合的方式一步合成制備出一元硼化物改性硅基超高溫陶瓷涂層MB2-SiC(M=Zr、Ta和Hf)。在一元硼化物改性硅基涂層研究基礎(chǔ)上,根據(jù)固溶體合成理論,采用過渡族金屬氧化物MxOy雙源共存的方式,同時添加ZrO2粉和Ta2O5粉來提供Zr源和Ta源,或同時添加HfO2粉和Ta2O5粉來提供Hf源和Ta源,結(jié)合B2O3粉,C粉和Si粉,經(jīng)過高溫?zé)崽幚?通過原位反應(yīng)法,可一步合成制備出硼化物固溶體(Zr,Ta)B2或(Ta,Hf)B2改性硅基超高溫陶瓷涂層。高溫靜態(tài)氧化試驗(yàn)結(jié)果表明,C/C復(fù)合材料在1773K靜態(tài)空氣中僅僅氧化25min后,試樣的失重百分?jǐn)?shù)高達(dá)23.1%。而在C/C表面制備出硼化物改性硅基超高溫陶瓷涂層后,試樣的氧化防護(hù)性能得到了顯著的提高。在ZrB2-SiC/SiC涂層、TaB2-SiC/SiC涂層以及HfB2-SiC/SiC涂層的保護(hù)下,三種試樣在1773K靜態(tài)空氣中分別氧化550、300以及265小時后,對應(yīng)的失重率為0.22%、1.1%以及1.6%。而在硼化物固溶體改性硅基超高溫陶瓷涂層(Zr,Ta)B2-SiC/SiC和(Ta,Hf)B2-SiC/SiC的保護(hù)下,試樣的氧化防護(hù)能力得到進(jìn)一步提升,分別可以在1773K靜態(tài)空氣中對C/C基體防護(hù)1412小時以及1480小時,而失重率僅為0.1%和0.57%,顯示了其極大的應(yīng)用潛力。熱重試驗(yàn)結(jié)果表明,硼化物對硅基超高溫陶瓷涂層的改性,可以有效提高涂層在室溫到1773K的動態(tài)測試環(huán)境中的氧化防護(hù)能力,純SiC涂層在測試結(jié)束后,試樣失重21.8%,而經(jīng)過ZrB2、TaB2、HfB2、(Zr,Ta)B2和(Ta,Hf)B2改性后,試樣的失重百分?jǐn)?shù)分別為10.3%、11.2%、8.7%、-1.8%和1.37%。在涂層表面生成的復(fù)相玻璃層是硼化物改性硅基超高溫陶瓷具有優(yōu)異氧化防護(hù)效果的主要原因。在氧化環(huán)境下,由于ZrB2改性相的存在,涂層表面覆蓋著一層由SiO2、ZrO2和ZrSiO4組合而成的Zr-Si-O復(fù)相玻璃層;TaB2改性相的存在,使得涂層表面覆蓋著一層由TaxOy、B2O3和SiO2等在內(nèi)的多重氧化物所組合而成的復(fù)相Ta-Si-O玻璃層;HfB2改性相的存在,使得涂層表面覆蓋著一層由HfO2、SiO2和HfSiO4所組合而成的Hf-Si-O復(fù)相玻璃層;而對于(Zr,Ta)B2和(Ta,Hf)B2固溶相而言,其在硅基超高溫陶瓷涂層中的存在,使得涂層表面分別覆蓋著一層由SiO2、ZrO2、ZrSiO4和TaxOy等組成的Zr-Ta-Si-O玻璃,以及由HfO2、SiO2、HfSiO4和TaxOy等組成的Hf-Ta-Si-O玻璃。在涂層表面生成的多重復(fù)相玻璃層在氧化環(huán)境下的防護(hù)機(jī)理呈現(xiàn)出明顯的差異。對于Zr-Si-O和Hf-Si-O復(fù)相玻璃層而言,由于高熔點(diǎn)氧化物ZrO2、HfO2、HfSiO4和ZrSiO4以不兼容相在二氧化硅玻璃中的存在,二者呈現(xiàn)出類似“釘扎相”的鑲嵌結(jié)構(gòu),“釘扎相”可以使玻璃層中生成的微裂紋在傳播的過程中“偏轉(zhuǎn)”或者“終止”,有效抑制了裂紋的擴(kuò)展和傳播,減少氧氣向基體的滲透,從而提高了涂層的氧化防護(hù)能力。對于Ta-Si-O復(fù)相玻璃層而言,由于多組元鉭氧化物與SiO2玻璃發(fā)生一定程度的熔合,呈現(xiàn)出由內(nèi)層SiO2玻璃層和外層復(fù)相Ta-Si-O玻璃層組合而成的雙重玻璃層;過渡族金屬鉭元素在SiO2玻璃中的存在,使得外層Ta-Si-O玻璃層的粘度以及穩(wěn)定性得以提高,展現(xiàn)出比SiO2玻璃更強(qiáng)的對微裂紋的限制作用;Ta-Si-O/SiO2玻璃展現(xiàn)出“微裂紋強(qiáng)化”的機(jī)理,通過在內(nèi)層SiO2玻璃中產(chǎn)生少量微裂紋,減少與空氣直接接觸的外層Ta-Si-O玻璃中的微裂紋數(shù)目以及降低形成“貫穿性裂紋”的可能性,從而進(jìn)一步提高其高溫穩(wěn)定性。而Zr-Ta-Si-O和Hf-Ta-Si-O玻璃是由具有鑲嵌結(jié)構(gòu)的Zr-Si-O玻璃和Hf-Si-O玻璃與具有“微裂紋強(qiáng)化”效果的Ta-Si-O玻璃層復(fù)合而成的,兼具了二者的優(yōu)異特性,展現(xiàn)出更加穩(wěn)定的氧化防護(hù)能力。氧乙炔燒蝕試驗(yàn)結(jié)果表明,經(jīng)過Zr B2、TaB2、HfB2、(Zr,Ta)B2和(Ta,Hf)B2改性后,涂層在熱流為2400KW/m2的氧乙炔焰測試45s后,試樣的質(zhì)量燒蝕率分別為3.58×10-3g/cm2、3.98×10-3 g/cm2、3.87×10-3 g/cm2、2.07×10-3 g/cm2和1.89×10-3 g/cm2,線燒蝕率分別為4.32×10-3mm/s、5.62×10-3 mm/s、4.72×10-3 mm/、2.73×10-3 mm/s和2.37×10-3 mm/s。由于氧乙炔焰的熱化學(xué)燒蝕以及機(jī)械剝蝕導(dǎo)致涂層發(fā)生損耗,而多組分氧化物的協(xié)同作用,是涂層燒蝕防護(hù)力得到提高的主要原因。分別對(Zr,Ta)B2相和(Ta,Hf)B2固溶體相改性硅基陶瓷涂層在1873K高溫風(fēng)洞沖刷條件下的氧化防護(hù)效果進(jìn)行了研究,結(jié)果表明,前者在1873K高溫風(fēng)洞燃?xì)猸h(huán)境下防護(hù)C/C基體76.5小時后,試樣最終在溫差較大的過渡區(qū)發(fā)生了斷裂;后者則有效防護(hù)C/C基體長達(dá)97小時,測試結(jié)束后,試樣沒有發(fā)生斷裂,基體也未發(fā)生明顯的氧化;在高溫風(fēng)洞沖刷環(huán)境下涂層中貫穿性裂紋的形成是試樣最終失效的主要原因。
[Abstract]:Oxidation sensitivity is the bottleneck of high temperature application of carbon / carbon (C/C) composites. Although silicon based ceramic coatings have better antioxidant effects in the temperature range of 1500-1600 C, the narrow defense temperature range and the long time use of ultra-high temperature are easy to produce holes and bubbles, which greatly restrict the oxidation of C/C Composites. In this paper, ZrB2, TaB2, HfB2, (Zr, Ta) B2 and (Ta, Hf) were prepared by in-situ inverse method. B2 modified silicon based coating was used to investigate its phase in 1773 K static air oxidation environment, room temperature -1773 K dynamic oxidation environment, 2400KW/m2 oxygen acetylene flame harsh high temperature ablation test environment and 1873K wind tunnel gas scour environment. The phase and morphology of the samples before and after oxidation test were measured by XRD, SEM and EDS test methods. The effect of boride modification on Microstructure and protective properties of silicon based ultra-high temperature ceramic coating was investigated and its oxidation failure mechanism was investigated. The main contents and results were as follows: the transition metal oxide MxOy (MxOy=ZrO2, Ta2O5 and HfO2) was selected as the transition metal M in the ultra-high temperature ceramic boride MB2. Source material, B2O3 powder is used as source of B, C powder is used as carbon source and silicon powder is used as source of Si. In situ reaction method, a one element boride modified silicon based super high temperature ceramic coating MB2-SiC (M=Zr, Ta and Hf) is prepared by the method of heat treatment in situ, through the combination of carbon thermo reduction reaction and solid state reaction. Based on the theory of solid solution synthesis, the ZrO2 powder and Ta2O5 powder are added to provide Zr source and Ta source, or HfO2 powder and Ta2O5 powder are added to provide Hf source and Ta source at the same time, and HfO2 powder and Ta2O5 powder are added at the same time, and B2O3 powder, C powder and Si powder are combined with B2O3 powder, C powder and Si powder. Through the high temperature heat treatment, the preparation can be made by one step synthesis by in situ reaction method. Boride solid solution (Zr, Ta) B2 or (Ta, Hf) B2 modified silicon based super high temperature ceramic coating. High temperature static oxidation test results show that the weight loss percentage of the C/C composite in 1773K static air is high as high as 23.1%. and the oxidation protection of the specimen after the preparation of a boride modified silicon based super high temperature ceramic coating on the C/C surface With the protection of ZrB2-SiC/SiC coating, TaB2-SiC/SiC coating and HfB2-SiC/SiC coating, three samples were oxidized for 550300 and 265 hours in the static air of 1773K, and the corresponding weight loss rate was 0.22%, 1.1% and 1.6%. in the boride solid solution modified silicon based ultra-high temperature ceramic coating (Zr, Ta) B2-SiC/SiC and (T). Under the protection of a, Hf) B2-SiC/SiC, the oxidation protection ability of the sample is further improved, which can protect C/C matrix for 1412 hours and 1480 hours respectively in the static air of 1773K, and the weight loss rate is only 0.1% and 0.57%, which shows its great potential application. To effectively improve the oxidation protection ability of the coating in the dynamic testing environment at room temperature to 1773K, the pure SiC coating was weighed 21.8% after the test, and the weight loss percentage of the sample was 10.3%, 11.2%, 8.7% after ZrB2, TaB2, HfB2, (Zr, Ta) B2 and (Ta, Hf) B2, respectively, and the composite phase glass layer formed on the surface of the coating was boron. The main reason for the excellent oxidation protection effect of the modified silicon based super high temperature ceramics is that the coating surface is covered with a layer of Zr-Si-O complex glass layer formed by the combination of SiO2, ZrO2 and ZrSiO4 in the oxidation environment. The existence of TaB2 modified phase makes the coating surface covered with a layer of TaxOy, B2O3 and SiO2, and so on. The complex phase Ta-Si-O glass layer composed of multiple oxides; the presence of HfB2 modified phase makes the coating surface covered with a layer of Hf-Si-O complex glass composed of HfO2, SiO2 and HfSiO4; and for the (Zr, Ta) B2 and (Ta, Hf) B2 solid solution, the existence of its presence in the silicon based ultra high temperature ceramic coating makes the coating surface covered separately. A layer of Zr-Ta-Si-O glass consisting of SiO2, ZrO2, ZrSiO4 and TaxOy, as well as Hf-Ta-Si-O glass consisting of HfO2, SiO2, HfSiO4 and TaxOy. The protective mechanism of the multiple duplicated glass layer on the coating surface is obviously different in the oxidation environment. For Zr-Si-O and Hf-Si-O complex glass layers, because of high melting point oxide ZrO2, HfO2, HfSiO4 and ZrSiO4 are in the presence of incompatible phase in silica glass. The two presents a mosaic structure similar to "pinning phase". "Pinning phase" can "deflect" or "terminate" in the propagation of the microcracks produced in the glass layer, which effectively inhibits the propagation and propagation of the cracks, and reduces the permeability of oxygen to the matrix. For the Ta-Si-O composite glass layer, because the multicomponent tantalum oxide is fused with the SiO2 glass to a certain extent, the double glass layer formed by the combination of the inner SiO2 glass layer and the outer complex Ta-Si-O glass layer is presented, and the existence of the over transition metal tantalum in the SiO2 glass is made. The viscosity and stability of the Ta-Si-O glass layer in the outer layer is improved, showing a stronger effect on the micro crack than the SiO2 glass; Ta-Si-O/SiO2 glass shows the mechanism of "micro crack strengthening", and a small amount of micro cracks are produced in the inner SiO2 glass to reduce the number of micro cracks in the outer Ta-Si-O glass directly contact with the air. And reduce the possibility of forming a "penetrating crack" to further improve its high temperature stability. Zr-Ta-Si-O and Hf-Ta-Si-O glass are composed of Zr-Si-O glass and Hf-Si-O glass with inlaid structure and the Ta-Si-O glass layer with "micro crack strengthening" effect, with the excellent characteristics of the two, showing more stability. The results of oxygen acetylene ablation test showed that after Zr B2, TaB2, HfB2, (Zr, Ta) B2 and (Ta, Hf) B2 modification, the quality ablative rate of the coating was 3.58 * * * * 10-3, 1.89 * 10-3 and 1.89 * 10-3. 4.32 x 10-3mm/s, 5.62 x 10-3 mm/s, 4.72 x 10-3 mm/, 2.73 x 10-3 mm/s and 2.37 x 10-3 mm/s. caused the coating loss due to the thermal chemical ablation of oxyacetylene flame and mechanical erosion, and the synergistic effect of the multi component oxide is the main reason for the improvement of the coating's ablation protection force. Respectively (Zr, Ta) B2 phase and (Ta, Hf) B2 solid solution, respectively. The oxidation protection effect of phase modified silicon based ceramic coating under the condition of 1873K high temperature wind tunnel was studied. The results showed that the former was finally broken in the transition zone with larger temperature difference in the 1873K high temperature wind tunnel gas environment for 76.5 hours, while the latter effectively protected the C/C matrix for up to 97 hours. After the test, the test was completed. There is no fracture in the specimen and no obvious oxidation occurs in the matrix. The formation of the penetrating crack in the coating of the high temperature wind tunnel is the main reason for the final failure of the specimen.
【學(xué)位授予單位】：西北工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TQ174.758.16

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相關(guān)期刊論文 前1條

1 程基偉,羅瑞盈,王天民;炭/炭復(fù)合材料高溫抗氧化研究的現(xiàn)狀[J];炭素技術(shù);2001年05期

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