發(fā)布時間：2018-10-29 21:59

【摘要】：碳化硅(SiC)陶瓷是一種具備良好的高溫強(qiáng)度、熱導(dǎo)率可達(dá)到88W·m~(-1)·K~(-1)、密度僅為3.1～3.2g·cm~(-3)、熱膨脹系數(shù)低、抗熱震性能優(yōu)異、耐酸堿腐蝕、耐磨損性能極其優(yōu)越的結(jié)構(gòu)材料,因此廣泛應(yīng)用在航空航天領(lǐng)域、化工領(lǐng)域、核能、微電子和運(yùn)輸?shù)阮I(lǐng)域。將碳化硅陶瓷制備成大尺寸部件或者是滿足特定應(yīng)用的復(fù)雜形狀的碳化硅陶瓷部件,在實(shí)際的工程應(yīng)用中可擴(kuò)展碳化硅陶瓷的應(yīng)用范圍。因此,碳化硅陶瓷新型連接工藝具有重要的研究意義。本論文主要探討了薄膜復(fù)合釬料的制備及其應(yīng)用在碳化硅陶瓷連接中的連接機(jī)理與性能。此外,研究了中間層材料對碳化硅陶瓷與TC4鈦合金連接工藝對微觀結(jié)構(gòu)以及性能的影響。采用流延成型工藝,制備出含體積分?jǐn)?shù)為10～35%的分別摻SiC陶瓷顆粒、TiC陶瓷顆粒、B4C陶瓷顆粒的Ag-Cu-Ti基的薄膜復(fù)合釬料。通過分散劑種類、分散劑含量、粘結(jié)劑含量、固含量對漿料流變性能的調(diào)節(jié),制備出了漿料流變性能良好,適合流延成型的漿料。最佳配比是選用蓖麻油磷酸酯作為分散劑,蓖麻油磷酸酯的質(zhì)量分?jǐn)?shù)為5%,粘結(jié)劑PVB的質(zhì)量分?jǐn)?shù)為2.6%,固含量的體積分?jǐn)?shù)為26%。以此配比,流延成型后的薄膜復(fù)合釬料具備厚度可控、熱膨脹系數(shù)可調(diào)、陶瓷顆粒均勻分布在Ag-Cu-Ti基體中、具有一定的柔韌性可以隨意的裁切成任意形狀的特點(diǎn),有利于后續(xù)的碳化硅陶瓷的釬焊連接。采用釬焊連接工藝將制備的薄膜復(fù)合釬料用于碳化硅陶瓷連接。研究了添加不同體積分?jǐn)?shù)的陶瓷顆粒的薄膜復(fù)合釬料對碳化硅陶瓷連接性能和微觀結(jié)構(gòu)的影響。結(jié)果發(fā)現(xiàn),薄膜復(fù)合釬料在焊溫度為900℃、保溫時間為10min的條件下都可用來碳化硅陶瓷連接且整個連接界面無裂紋、氣孔等缺陷�？拷覆奶蓟韪浇姆磻�(yīng)層產(chǎn)物是TiC相和Ti5Si3相。B4C陶瓷顆粒周圍包裹層為TiB2相和TiC相,SiC陶瓷顆粒周圍有TiC相和Ti5Si3相,TiC陶瓷顆粒與其他物質(zhì)不反應(yīng)。薄膜復(fù)合釬料中添加體積分?jǐn)?shù)為20%SiC陶瓷時,其連接件的抗彎強(qiáng)度最高,可達(dá)260±19MPa。陶瓷顆粒、母材碳化硅陶瓷附近反應(yīng)層厚度、陶瓷顆粒周圍界面反應(yīng)是影響連接強(qiáng)度的主要因素。以熱膨脹系數(shù)介于碳化硅陶瓷與TC4鈦合金的金屬Ta、Nb、W以及彈性模量較小的Cu為中間層連接碳化硅陶瓷與TC4鈦合金。采用Cu作為中間層實(shí)現(xiàn)了二者的連接,連接溫度、保溫時間對連接接頭的影響。結(jié)合微觀結(jié)構(gòu)與力學(xué)性能,得出了反應(yīng)層厚度與擴(kuò)散層厚度是影響連接強(qiáng)度的最主要原因。在釬焊溫度為860℃時、保溫時間為20min時,連接部件的抗彎強(qiáng)度達(dá)到最大為149.6MPa。連接部件經(jīng)500℃的10次淬火后,強(qiáng)度降到14±6MPa。主要原因是熱震過程中間層Cu氧化失去原有的塑性形變,因此難以緩解連接接頭處的熱應(yīng)力。
[Abstract]:Silicon carbide (SiC) ceramics have good high temperature strength. The thermal conductivity can reach 88W m ~ (-1) K ~ (-1), the density is only 3.1g cm~ (-3), the coefficient of thermal expansion is low, and the thermal shock resistance is excellent. It is widely used in the fields of aerospace, chemical industry, nuclear energy, microelectronics, transportation and so on. Silicon carbide ceramics can be made into large size parts or silicon carbide ceramic parts with complex shapes which can be used for specific applications. The application scope of silicon carbide ceramics can be expanded in practical engineering applications. Therefore, it is of great significance to study the new bonding process of silicon carbide ceramics. In this paper, the preparation of thin film composite solder and its application in the bonding of silicon carbide ceramics are discussed. In addition, the effect of interlayer material on microstructure and properties of silicon carbide ceramics and TC4 titanium alloy was studied. The thin film brazing filler metals containing 1035% SiC ceramic particles, TiC ceramic particles and B4C ceramic particles were prepared by the casting process. By adjusting the content of dispersant, dispersant content, binder content and solid content to the rheological properties of slurry, the slurry with good rheological property was prepared and suitable for casting. The best proportion is castor oil phosphate as dispersant, the mass fraction of castor oil phosphate is 5, the mass fraction of binder PVB is 2.6, the volume fraction of solid content is 26. With this ratio, the film composite solder after casting has the characteristics of controllable thickness, adjustable coefficient of thermal expansion, uniform distribution of ceramic particles in the Ag-Cu-Ti matrix, and a certain flexibility that can be cut into arbitrary shape at will. It is advantageous to the brazing bonding of the subsequent sic ceramics. The thin film composite brazing filler metal was used for bonding silicon carbide ceramic by brazing process. The effect of thin film brazing filler metal with different volume fraction of ceramic particles on the bonding properties and microstructure of sic ceramics was studied. The results show that when the welding temperature is 900 鈩，

本文編號：2298950