發(fā)布時(shí)間：2019-06-12 15:23

【摘要】：作為一種隔熱防護(hù)的結(jié)構(gòu)體系,在苛刻的服役環(huán)境下熱障涂層能有效提高渦輪葉片的服役溫度,降低了服役環(huán)境對(duì)于渦輪葉片金屬基底的損傷。高溫環(huán)境下熱障涂層體系難以預(yù)測(cè)的界面失效及脫落問題極大限制了其廣泛應(yīng)用和可靠性評(píng)價(jià)。因此,目前亟待發(fā)展新型實(shí)驗(yàn)測(cè)試技術(shù)及實(shí)驗(yàn)設(shè)備完善熱障涂層體系的高溫力學(xué)性能,對(duì)于有效掌握其破壞機(jī)理具有重要的意義。本文改進(jìn)了傳統(tǒng)測(cè)試設(shè)備,發(fā)展了一種1600°C范圍內(nèi)材料力學(xué)性能測(cè)試的新方法,對(duì)傳統(tǒng)的熱障涂層體系進(jìn)行了不同服役溫度下的實(shí)驗(yàn)和裂紋失效機(jī)制分析。主要內(nèi)容如下:第一,對(duì)傳統(tǒng)的DIC測(cè)試設(shè)備進(jìn)行升級(jí)改造。自主配置了兩個(gè)高溫放大鏡頭以及藍(lán)光濾鏡,引進(jìn)了用于高溫實(shí)驗(yàn)的補(bǔ)償光源,充分解決了服役高溫下實(shí)驗(yàn)的放大倍數(shù)不夠、熱輻射和光線不足等不穩(wěn)定因素;發(fā)展了一種新型測(cè)試方法,可以實(shí)現(xiàn)1600°C范圍內(nèi)的材料力學(xué)性能測(cè)試,在位移場(chǎng)和應(yīng)變場(chǎng)基準(zhǔn)上驗(yàn)證了其可行性;并成功授權(quán)了一項(xiàng)高溫散斑制備方法的發(fā)明專利(CN103792117A)。第二,基于上述改進(jìn)的設(shè)備和方法,在常溫和800°C~1000°C溫度下對(duì)粘結(jié)層-基底結(jié)構(gòu)進(jìn)行拉伸實(shí)驗(yàn),準(zhǔn)確獲得了整個(gè)拉伸實(shí)驗(yàn)中粘結(jié)層材料表面位移場(chǎng)和應(yīng)變場(chǎng)的演化過程。通過對(duì)關(guān)鍵階段和初始裂紋準(zhǔn)確數(shù)據(jù)的提取,得到了隨著溫度升高臨界斷裂應(yīng)變由0.35%逐漸地降低到0.21%;臨界斷裂強(qiáng)度由700 MPa降低到252 MPa;臨界剪切強(qiáng)度由117.6 MPa降低到42.4 MPa,充分表明了實(shí)驗(yàn)溫度對(duì)實(shí)驗(yàn)結(jié)果的影響;結(jié)合實(shí)驗(yàn)過程中數(shù)字圖像相關(guān)法計(jì)算得到的全場(chǎng)應(yīng)變?cè)茍D和掃描電鏡微觀形貌圖,詳細(xì)探討了不同服役溫度下粘結(jié)層-基底結(jié)構(gòu)失效機(jī)制。第三,利用搭建的測(cè)試平臺(tái)在常溫和800°C~1000°C服役溫度下進(jìn)行拉伸實(shí)驗(yàn),計(jì)算分析得到EB-PVD熱障涂層體系表面位移場(chǎng)和應(yīng)變場(chǎng)的演化過程。提取出關(guān)鍵階段和初始裂紋相關(guān)數(shù)據(jù)并結(jié)合拉曼光譜法測(cè)試得到的陶瓷層表面殘余應(yīng)力值,得到EB-PVD熱障涂層體系陶瓷層臨界斷裂應(yīng)變逐漸由0.45%降低到0.12%;相對(duì)應(yīng)的臨界斷裂強(qiáng)度由239.7 MPa降低到74 MPa;臨界剪切強(qiáng)度由53.8 MPa降低到20.5 MPa,充分表明了實(shí)驗(yàn)溫度對(duì)實(shí)驗(yàn)結(jié)果的影響;相似地,借助實(shí)驗(yàn)后試樣的宏微觀形貌圖和數(shù)字圖像相關(guān)法計(jì)算得到的全場(chǎng)應(yīng)變?cè)茍D,詳細(xì)探討了不同服役溫度下三層結(jié)構(gòu)EB-PVD熱障涂層體系失效機(jī)制。
[Abstract]:As a kind of thermal insulation protection structure system, the thermal barrier coating can effectively increase the service temperature of turbine blades and reduce the damage to the metal substrate of turbine blades in harsh service environment. The interface failure and shedding of thermal barrier coating system which is difficult to predict in high temperature environment greatly limit its wide application and reliability evaluation. Therefore, it is urgent to develop new experimental testing technology and experimental equipment to improve the high temperature mechanical properties of thermal barrier coating system, which is of great significance for effectively mastering its failure mechanism. In this paper, the traditional testing equipment is improved, and a new method for testing the mechanical properties of materials in the range of 1600 擄C is developed. the experiments and crack failure mechanism analysis of the traditional thermal barrier coating system at different service temperatures are carried out. The main contents are as follows: first, upgrade the traditional DIC test equipment. Two high temperature magnifying lenses and blue light filters are equipped independently, and the compensation light source for high temperature experiment is introduced, which fully solves the unstable factors such as insufficient magnification, thermal radiation and insufficient light in the service high temperature experiment, and a new testing method is developed, which can realize the mechanical properties test in the range of 1600 擄C, and its feasibility is verified on the in-situ shift field and strain field benchmark. A patent for the preparation of high temperature speckle (CN103792117A) has been successfully authorized. Secondly, based on the above improved equipment and method, the tensile experiments of bonding layer-substrate structure at room temperature and 800 擄C ~ 1000 擄C were carried out, and the evolution process of surface displacement field and strain field of bonding layer material in the whole tensile test was obtained accurately. Through the extraction of the accurate data of the key stage and the initial crack, it is obtained that the critical fracture strain decreases from 0.35% to 0.21% with the increase of temperature, and the critical fracture strength decreases from 117.6 MPa to 252 MPa; critical shear strength from 117.6 MPa to 42.4 MPa, which fully indicates the effect of the experimental temperature on the experimental results. Combined with the whole field strain cloud diagram and scanning electron microscope microtopography calculated by digital image correlation method, the failure mechanism of bonding layer-substrate structure at different service temperatures is discussed in detail. Thirdly, the tensile experiments were carried out at room temperature and 800 擄C ~ 1000 擄C, and the evolution process of surface displacement field and strain field of EB-PVD thermal barrier coating system was calculated and analyzed. The residual stress on the surface of ceramic layer measured by Raman spectroscopy was obtained by extracting the relevant data of critical stage and initial crack, and the critical fracture strain of ceramic layer in EB-PVD thermal barrier coating system gradually decreased from 0.45% to 0.12%, and the corresponding critical fracture strength decreased from 239.7 MPa to 74 MPa;. The decrease of critical shear strength from 53.8 MPa to 20.5 MPa, fully shows the effect of experimental temperature on the experimental results. Similarly, the failure mechanism of three-layer EB-PVD thermal barrier coating system at different service temperatures is discussed in detail with the help of the macro and micro morphology of the sample and the full field strain cloud diagram calculated by digital image correlation method.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG174.4

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本文編號(hào)：2498103