【摘要】：隨著高超聲速飛行器飛行速度的不斷提升,服役環(huán)境也越來(lái)越惡劣,為保證航天飛行器安全穩(wěn)定飛行,必須開(kāi)展飛行器鼻錐等關(guān)鍵熱端部件的熱防護(hù)問(wèn)題的研究。作為高超聲速飛行器關(guān)鍵熱端結(jié)構(gòu)件,鼻錐在飛行時(shí)將面臨非常嚴(yán)重的氣動(dòng)加熱,為保證高超聲速飛行器的整體性能,飛行器鼻錐不允許有較大變形,因此,飛行器鼻錐熱防護(hù)結(jié)構(gòu)材料必須滿足長(zhǎng)時(shí)間抗氧化和耐燒蝕等性能要求。超高溫陶瓷復(fù)合材料因具有耐高溫、抗氧化燒蝕等優(yōu)異特性,是飛行器鼻錐等關(guān)鍵熱端部件的首選材料之一,但超高溫陶瓷材料難以燒結(jié)致密化以及本征脆性等特點(diǎn)加大了高性能鼻錐熱防護(hù)結(jié)構(gòu)材料的制備和加工難度。因此,開(kāi)展鼻錐熱防護(hù)結(jié)構(gòu)超高溫陶瓷材料的制備、加工以及相關(guān)性能考核具有重要的意義。本文根據(jù)飛行器鼻錐熱防護(hù)結(jié)構(gòu)需求,結(jié)合飛行器鼻錐的服役特點(diǎn),設(shè)計(jì)了前端呈半球狀后端呈圓柱狀的組合式鼻錐熱防護(hù)結(jié)構(gòu),并采用ANSYS軟件建立了模型,對(duì)建立的鼻錐熱防護(hù)結(jié)構(gòu)件模型進(jìn)行了溫度場(chǎng)分析。分析結(jié)果表明鼻尖部溫度最高,并依據(jù)溫度場(chǎng)分析結(jié)果選取鼻錐熱防護(hù)材料。本文選擇Zr B2-Si C-G超高溫陶瓷材料作為鼻錐熱防護(hù)結(jié)構(gòu)材料的制備體系。采用熱壓燒結(jié)工藝制備材料,與以前研究不同,本次制備出了綜合性能優(yōu)異的大尺寸鼻錐熱防護(hù)結(jié)構(gòu)材料,并通過(guò)組分優(yōu)化和工藝優(yōu)化保證材料的致密性,以及良好的力學(xué)性能。研究了不同參數(shù)對(duì)Zr B2-20vol.%Si C-G陶瓷材料的致密度、彎曲強(qiáng)度和斷裂韌性等性能的影響,如石墨含量、燒結(jié)溫度等。試驗(yàn)結(jié)果表明:1900℃、30MPa和1h條件下熱壓燒結(jié)的Zr B2-20vol.%Si C-10vol.%G材料綜合性能較為優(yōu)異,其中彎曲強(qiáng)度為487MPa,斷裂韌性為6.2MPa.m1/2,致密度為99.7%。本文采用了ELID磨削技術(shù)對(duì)該超高溫陶瓷燒結(jié),然后對(duì)材料進(jìn)行加工成型,并對(duì)該熱結(jié)構(gòu)件磨削表面粗糙度進(jìn)行正交試驗(yàn),同時(shí)分析了磨削工藝參數(shù)與表面粗糙度之間的關(guān)系。試驗(yàn)結(jié)果表明最佳磨削工藝組合為:粒度w40#、砂輪線速度26.2m/s、磨削深度0.005mm、工件轉(zhuǎn)速35r/min。同時(shí)采用超聲檢測(cè)(UT)和X射線檢測(cè)(RT)相結(jié)合的方法對(duì)鼻錐熱防護(hù)結(jié)構(gòu)超高溫陶瓷材料進(jìn)行無(wú)損檢測(cè),檢測(cè)結(jié)果表明陶瓷材料內(nèi)部和表面的微觀孔隙含量比較少,表明該鼻錐熱結(jié)構(gòu)件材料具有優(yōu)異的綜合性能。研究了Zr B2-20vol.%Si C-10vol.%G鼻錐熱防護(hù)結(jié)構(gòu)超高溫陶瓷材料的抗氧化燒蝕行為。地面考核實(shí)驗(yàn)結(jié)果表明該鼻錐熱防護(hù)結(jié)構(gòu)材料的宏觀形貌相對(duì)完好,能保持良好的完整性;且沒(méi)有出現(xiàn)微裂紋,表現(xiàn)出較強(qiáng)的抗氧化燒蝕能力。同時(shí)結(jié)合鼻錐熱防護(hù)結(jié)構(gòu)件的地面考核實(shí)驗(yàn)結(jié)果,對(duì)超高溫陶瓷材料進(jìn)行了氧化燒蝕機(jī)理分析。
[Abstract]:With the increasing flight speed of hypersonic vehicle, the service environment is becoming worse and worse. In order to ensure the safety and stability of space vehicle, it is necessary to study the thermal protection of the key hot end parts such as nose cone. As the key hot end structure of hypersonic vehicle, nose cone will face very serious aerodynamic heating in flight. In order to ensure the overall performance of hypersonic vehicle, the nose cone is not allowed to be deformed. The thermal protection materials of the nose cone of aircraft must meet the requirements of long time oxidation resistance and ablation resistance. Because of its excellent properties of high temperature resistance, oxidation resistance and ablation, ultra-high temperature ceramic composite is one of the first choice materials for the key hot end parts such as nose cone of aircraft. However, the characteristics of ultra-high temperature ceramic materials are difficult to sintering densification and intrinsic brittleness, which makes the preparation and processing of high performance nasal cone thermal protective structure materials more difficult. Therefore, it is of great significance to prepare, process and evaluate the properties of ultra-high temperature ceramic materials for the thermal protection structure of nasal cone. According to the requirements of the thermal protection structure of the nose cone of the aircraft and the service characteristics of the nose cone of the aircraft, the combined structure of the thermal protection of the nose cone with a cylindrical front end is designed, and the model is established by using ANSYS software. The temperature field of the thermal protection structure model of nasal cone is analyzed. The results show that the temperature of nasal tip is the highest, and the thermal protection material of nasal cone is selected according to the results of temperature field analysis. In this paper, Zr B2-Si C-G ultrahigh temperature ceramic material is selected as the preparation system of the thermal protection structure material of nasal cone. The hot pressing sintering process was used to prepare the materials. Different from the previous research, a large size thermal protection structure material with excellent comprehensive properties was prepared, and the densification of the material was ensured by component optimization and process optimization. And good mechanical properties. The effects of different parameters on the density, bending strength and fracture toughness of Zr B2-20vol.%Si C-G ceramics were studied, such as graphite content, sintering temperature and so on. The experimental results show that the composite properties of Zr B2-20vol.%Si C-10vol.%G sintered at 30 MPA at 1: 1900 鈩，

本文編號(hào)：2184796