本文選題：NiCoCrAlY-Cr_2O_3-Ag + 涂層�。� 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)》2017年博士論文

【摘要】：目前先進(jìn)航空發(fā)動(dòng)機(jī)的高壓壓氣機(jī)和低壓渦輪部位采用刷式封嚴(yán)結(jié)構(gòu),由于刷式封嚴(yán)的主要部件刷絲需要在高溫燃?xì)鈼l件下與高速運(yùn)轉(zhuǎn)的轉(zhuǎn)子軸表面摩擦接觸,因此為了降低刷絲與轉(zhuǎn)子軸表面的磨損,通常利用熱噴涂技術(shù)在轉(zhuǎn)子軸表面制備一層高溫自潤滑耐磨涂層。由于使役環(huán)境惡劣,該涂層不僅要具有寬溫域自潤滑減摩耐磨效果,還應(yīng)該具備良好的高溫抗氧化、耐熔鹽腐蝕、耐熱循環(huán)等性能。本論文采用化學(xué)還原、化學(xué)鍍、離心噴霧造粒以及固態(tài)合金化技術(shù)制備了 Ag、Ag-Mo、CoNiCrAlY-Cr_2O_3以及NiCoCrAlY-Cr_2O_3四種粉體,并采用等離子噴涂技術(shù)制備了 CoNiCrAlY-Cr_2O_3、NiCoCrAlY-Cr_2O_3、NiCoCrAlY-Cr_2O_3-Ag 以及 NiCoCrAlY-Cr_2O_3-AgMo 四種復(fù)合涂層,對復(fù)合涂層的結(jié)構(gòu)以及性能進(jìn)行了系統(tǒng)研究,揭示了復(fù)合涂層在苛刻環(huán)境條件下的結(jié)構(gòu)與性能變化規(guī)律及相關(guān)作用機(jī)理。主要研究內(nèi)容和結(jié)果如下:(1)對等離子噴涂CoNiCrAlY-Cr_2O_3和NiCoCrAlY-Cr_2O_3復(fù)合涂層的摩擦磨損性能、抗氧化性和抗熔鹽腐蝕性能進(jìn)行了研究。摩擦磨損結(jié)果表明:隨著溫度的上升,兩種涂層的摩擦系數(shù)均呈下降趨勢。600℃以下,CoNiCrAlY-Cr_2O_3涂層的摩擦系數(shù)略低于NiCoCrAlY-Cr_2O_3涂層;600℃以上,兩種涂層的摩擦系數(shù)相差不大。涂層的磨損量均在10-5mm~3/Nm數(shù)量級。涂層的氧化實(shí)驗(yàn)表明:在800℃下,NiCoCrAlY-Cr_2O_3涂層的抗氧化性略優(yōu)于CoNiCrAlY-Cr_2O_3涂層。對兩種涂層進(jìn)行氧化動(dòng)力學(xué)分析,其氧化動(dòng)力學(xué)曲線分為大斜率直線、拋物線和小斜率直線三個(gè)階段,涂層均具有較好的抗氧化性能。氧化后表面生成的尖晶石氧化物以及涂層中沉積的Cr_2O_3對涂層起到了保護(hù)作用。熔鹽腐蝕實(shí)驗(yàn)表明:由于Co·Co_3S_2 比Ni·Ni_3S_2共晶體在800℃下相對穩(wěn)定,并且Co基合金具有更好的耐S腐蝕性能,因此CoNiCrAlY-Cr_2O_3涂層的抗熔鹽腐蝕性能優(yōu)于NiCoCrAlY-Cr_2O_3涂層。(2)研究了 Ag膜在硬質(zhì)基體表面的潤滑性能,發(fā)現(xiàn)Ag膜在常溫下的摩擦系數(shù)僅有0.2。以Ag為潤滑劑,采用等離子噴涂技術(shù)制備了 NiCoCrAlY-Cr_2O_3、NiCoCrAlY-Cr_2O_3-10Ag以及NiCoCrAlY-Cr_2O_3-30Ag三種復(fù)合涂層,涂層結(jié)構(gòu)致密,孔隙率都在2.5%左右。NiCoCrAlY-Cr_2O_3涂層的顯微硬度約為650HV0.2。隨著Ag的加入,涂層的顯微硬度降低,但是結(jié)合強(qiáng)度有所提高。NiCoCrAlY-Cr_2O_3-30Ag涂層的結(jié)合強(qiáng)度達(dá)到53MPa,比NiCoCrAlY-Cr_2O_3提高了 17MPa。涂層的摩擦磨損性能表明:與NiCoCrAlY-Cr_2O_3涂層相比,加入10%Ag后,涂層的摩擦系數(shù)從室溫到800℃有所降低,在600℃達(dá)到最低值0.3。當(dāng)加入30%Ag時(shí),涂層在高溫下的摩擦系數(shù)和磨損量都顯著增高。摩擦機(jī)理分析表明:低溫下,Ag在涂層表面鋪展成膜發(fā)揮潤滑作用;高溫下,Ag擴(kuò)散到表面并發(fā)生熔融軟化,過量的Ag造成涂層嚴(yán)重的黏著磨損和塑性變形。涂層的熱循環(huán)及氧化實(shí)驗(yàn)表明:加入Ag后,涂層的抗熱震性能提高,但是氧化增重略高于NiCoCrAlY-Cr_2O_3涂層。(3)以Ag-Mo作為復(fù)合固體潤滑劑,采用等離子噴涂制備了NiCoCrAlY-Cr_2O_3-10AgMo 和 NiCoCrAlY-Cr203-15AgMo 兩種復(fù)合涂層。兩種涂層的顯微硬度均約為600HV0.2。涂層的結(jié)合強(qiáng)度分別為42±2MPa以及45±5MPa。涂層的摩擦磨損性能表明:加入Ag-Mo復(fù)合固體潤滑劑的涂層從室溫到800℃內(nèi)具有優(yōu)異的潤滑性能,在800℃摩擦系數(shù)僅有0.3左右。磨損量從室溫到800℃都保持在10-5mm~3/Nm數(shù)量級。600℃以上,摩擦表面生成的NiMoO_4和Ag_2MoO_4化合物有效降低了涂層的摩擦磨損。此外,較高的載荷會(huì)促進(jìn)Ag,Mo與O_2反應(yīng)生成Ag_2MoO_4潤滑膜的過程,并有助于壓實(shí)磨屑形成保護(hù)性釉質(zhì)層,提高涂層潤滑耐磨性能。(4)用冷等靜壓和高溫?zé)Y(jié)法制備了 Ag-Mo復(fù)合材料,測試并分析了材料的摩擦磨損性能和潤滑機(jī)理。結(jié)果發(fā)現(xiàn):低溫下,鋪展在摩擦表面的Ag膜起到潤滑作用;高溫下摩擦表面生成的一系列低熔點(diǎn)鉬酸銀化合物降低了涂層的摩擦磨損。通過對Ag-Mo-O_2固相反應(yīng)機(jī)理的研究,建立了 Ag-Mo-O_2三元體系生成Ag_2MoO_4的固相反應(yīng)模型。研究發(fā)現(xiàn):Ag_2MoO_4在空氣氣氛下1000℃以內(nèi)不分解也不揮發(fā),并且對NiCoCrAlY-Cr_2O_3涂層具有良好的潤濕性。(5)有限元模擬計(jì)算表明:涂層的彈性模量越高,封嚴(yán)層與粘結(jié)層之間的應(yīng)力梯度越大,在熱循環(huán)過程中封嚴(yán)涂層越容易產(chǎn)生裂紋并脫落。在涂層中加入Ag可使彈性模量降低34%,改善涂層與基體熱膨脹系數(shù)的匹配性,從而提高涂層的抗熱震性能。
[Abstract]:At present, the high pressure compressor and the low pressure turbine part of Advanced Aero engine use a brush seal structure. Because the brush seal is the main part of the brush, the brush wire needs to contact with the surface of the rotor shaft running at high speed under the condition of high temperature gas. So in order to reduce the wear of the brush and the rotor shaft, the thermal spraying technology is usually used in the rotor shaft. A layer of high temperature self lubricating and wear-resistant coating is prepared on the surface. Due to the bad environment, the coating should not only have the effect of self lubrication and wear resistance in the wide temperature field, but also have good antioxidation, corrosion resistance and heat-resistant cycle. This paper is prepared by chemical reduction, electroless plating, centrifugal spray granulation and solid-state alloying technology. Four kinds of powders of Ag, Ag-Mo, CoNiCrAlY-Cr_2O_3 and NiCoCrAlY-Cr_2O_3 were used to prepare four kinds of composite coatings, CoNiCrAlY-Cr_2O_3, NiCoCrAlY-Cr_2O_3, NiCoCrAlY-Cr_2O_3-Ag and NiCoCrAlY-Cr_2O_3-AgMo. The structure and properties of the composite coatings were systematically studied. The main contents and results are as follows: (1) the friction and wear properties of the plasma sprayed CoNiCrAlY-Cr_2O_3 and NiCoCrAlY-Cr_2O_3 composite coatings, the oxidation resistance and the corrosion resistance of the molten salt were studied. The friction and wear results showed that with the increase of temperature, two The friction coefficient of the coating is below.600 C, and the friction coefficient of the CoNiCrAlY-Cr_2O_3 coating is slightly lower than that of the NiCoCrAlY-Cr_2O_3 coating; the friction coefficient of the two kinds of coatings is not quite different at 600 degrees C. The wear amount of the coating is at the order of 10-5mm~3/Nm. The oxidation test of the coating shows that the oxygen resistance of the NiCoCrAlY-Cr_2O_3 coating at 800 C The oxidation kinetics of two kinds of coatings was analyzed. The kinetic curves of the two coatings were divided into three stages: large slope straight line, parabolic line and small slope straight line. The coating had better oxidation resistance. The oxidation of the spinel formed on the surface after oxidation and the deposited Cr_2O_3 in the coating played a role in the coating. The corrosion test of molten salt showed that Co. Co_3S_2 was relatively stable at 800 C than Ni Ni_3S_2 eutectic, and Co based alloy had better corrosion resistance to S. Therefore, the corrosion resistance of CoNiCrAlY-Cr_2O_3 coating was better than that of NiCoCrAlY-Cr_2O_3 coating. (2) the lubrication performance of Ag film on the surface of hard matrix was studied, and Ag was found to find Ag. The friction coefficient of the film at normal temperature is only 0.2. Ag as lubricant. Three kinds of composite coatings, NiCoCrAlY-Cr_2O_3, NiCoCrAlY-Cr_2O_3-10Ag and NiCoCrAlY-Cr_2O_3-30Ag, are prepared by plasma spraying technology. The coating structure is compact and the porosity of the coating is about 2.5%.NiCoCrAlY-Cr_2O_3 coating with the addition of 650HV0.2. with Ag. The microhardness of the coating is reduced, but the bonding strength of the.NiCoCrAlY-Cr_2O_3-30Ag coating is up to 53MPa, and the friction and wear performance of the 17MPa. coating is increased than that of NiCoCrAlY-Cr_2O_3. Compared with the NiCoCrAlY-Cr_2O_3 coating, the friction coefficient of the coating decreases from room temperature to 800 C after adding 10%Ag, and the friction coefficient is reached at 600. When the minimum value of 0.3. is added to 30%Ag, the friction coefficient and wear amount of the coating increase significantly at high temperature. The analysis of the friction mechanism shows that at low temperature, the Ag spread into the coating surface to play the lubrication; at the high temperature, the Ag diffuses to the surface and melts and softens, and the excessive Ag causes the coating's serious adhesion and plastic deformation. The thermal evidence-based of the coating. The experiments of ring and oxidation show that the thermal shock resistance of the coating is increased after adding Ag, but the oxidation weight gain is slightly higher than that of the NiCoCrAlY-Cr_2O_3 coating. (3) two composite coatings of NiCoCrAlY-Cr_2O_3-10AgMo and NiCoCrAlY-Cr203-15AgMo are prepared by plasma spraying with Ag-Mo as a composite lubricant. The microhardness of the two kinds of coatings is about 600H The friction and wear properties of the V0.2. coating with the bonding strength of 42 + 2MPa and 45 + 5MPa. coatings show that the coating with Ag-Mo composite solid lubricants has excellent lubrication performance from room temperature to 800 C, and the friction coefficient is only about 0.3 at 800 C. The wear amount is kept at.600 degrees centigrade at 10-5mm~3/Nm order of magnitude from room temperature to 800 centigrade. The surface generated NiMoO_4 and Ag_2MoO_4 compounds effectively reduce the friction and wear of the coating. In addition, the higher load will promote the process of Ag, Mo and O_2 to produce Ag_2MoO_4 lubricating film, and help compacting the debris to form the protective glaze layer and improve the wear resistance of the coating. (4) the Ag-Mo composite is prepared by the cold isostatic pressure and the high temperature sintering method. The friction and wear properties and the lubrication mechanism of the material were tested and analyzed. It was found that the Ag film spreading on the friction surface was lubricated at low temperature, and a series of low melting point silver molybdate compounds produced at the friction surface at high temperature reduced the friction and wear of the coating. By the study of the mechanism of the solid state reaction of Ag-Mo-O_2, the Ag-Mo-O was established. The _2 three element system generates a solid state reaction model of Ag_2MoO_4. It is found that Ag_2MoO_4 does not evaporate within 1000 C in air and has good wettability to NiCoCrAlY-Cr_2O_3 coating. (5) finite element simulation shows that the higher the elastic modulus of the coating, the greater the stress gradient between the sealing layer and the bonding layer, and the heat of the coating. In the cycle process, the more easy the coating is, the more easy to produce the crack and fall off. Adding Ag in the coating can reduce the modulus of elasticity by 34%, improve the matching of the thermal expansion coefficient of the coating and the matrix, so as to improve the thermal shock resistance of the coating.

【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：V263;TG174.4

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