Low-melting-point titanium-base brazing alloys—part 1: Characteristics of two-, three-, and four-component filler metals

The melting point, microstructure, phase, and electrochemical behavior of Ti-21Ni-15Cu alloy, together with two-, three-, and four-component low-melting-point titanium-base brazing alloys, are presented in this paper. Five filler metals were selected for the study, in which melting points were measured by differential thermal analysis, phases identified by x-ray diffractometry, and corrosion behaviors tested by potentiodynamic polarization. The experimental results show that the three-component Ti-15Cu-15Ni and the newly developed Ti-21Ni-14Cu alloys exhibit the combination of lower melting point and superior corrosion resistance compared to the two-and four-component titanium alloys, 316L stainless steel, and a Co-Cr-Mo alloy in Hank’s solution at 37 °C. On a short time basis, the presence of Ti₂Ni and Ti₂Cu intermetallics in the Ti-15Cu-15Ni and Ti-21Ni-14Cu alloys should not be preferentially dissolved in galvanic corrosion with respect to the dissimilar Ti-6Al-4V alloy.     

Al-20Cu-9.6Si-xEr钎料对SiC_p/A356复合材料真空钎焊接头组织与性能的影响EI北大核心CSCD

采用不同铒含量的7组Al-20Cu-9.6Si-xEr钎料分别对SiCp/A356复合材料进行了真空钎焊。利用扫描电镜和能谱分析等方法对接头微观组织进行了观察和分析。通过剪切实验对钎焊接头的抗剪强度进行了测定,并对剪切断口的微观形貌进行了观察。结果表明：添加稀土后,钎焊接头的抗剪强度明显提高。当w（Er）=0%时,钎缝处SiC颗粒聚集严重,接头强度为43.5MPa;当w（Er）=0.05%时,钎缝边界无SiC颗粒的聚集,接头强度最高,达到68.6MPa;当w（Er）=0.1%-0.4%时,钎缝处SiC颗粒聚集趋势减弱,接头强度值在45.3-50.5MPa之间;当w（Er）=0.5%时,SiC颗粒分布在钎缝内部,接头强度明显提高,达到62.2MPa。     

连接SiCp/6063Al复合材料的Al-Si-Cu-Ce-Ti箔状钎料制备及其性能研究

采用快凝甩带技术制备了6组不同Ti含量的(Al-10Si-20Cu-0.05Ce)-xTi急冷箔状钎料,并对SiCp/6063Al复合材料进行真空钎焊,然后对钎料及接头的显微组织和性能进行分析。结果表明,急冷箔较常规铸态钎料的组织细小、均匀;固、液相线降低,熔化区间变窄;随着Ti含量的增加,急冷箔中片状Al-Si-Ti金属间化合物相增多,导致钎料脆性增加;6组钎料在复合材料上润湿性较差,但在6063Al合金上润湿性良好。在580℃钎焊温度、保温30min条件下,采用1%Ti含量急冷箔状钎料成功连接了SiCp/6063Al复合材料,钎焊接头组织致密、完整,急冷箔状钎料与6063Al合金基体连接界面可进行充分的冶金结合,且接头剪切强度达到104.9 MPa;钎焊前采用夹具增加接头压力可显著提高接头的连接质量。     

耐候防腐涂料的研究进展

综述了耐候防腐涂料的研究进展和提高常温固化防腐涂料耐候性能的几种途径,主要包括耐候型成膜物质的制备与改性,如含氟类、有机硅类、丙烯酸类等树脂,以及耐候型功能颜填料的添加,如钛白粉、纳米导电聚合物等填料和各类光稳定剂等,并对提高常温固化防腐涂料耐候性能可能的方法进行了展望。     

高体积比SiCp/6063Al复合材料的铝基钎料制备及钎焊工艺研究

采用快速甩带技术制备了(Al-10Si-20Cu-0.05Ce)-1Ti(质量分数/%)急冷箔状钎料,并对60%体积分数的SiCp/6063Al复合材料进行真空钎焊实验,然后对钎料及接头的显微组织与性能进行测定和分析。结果表明,急冷钎料的微观组织细小、成分均匀,厚80~90μm,主要包含Al、CuAl2、Si和Al2Ti等相。当升高钎焊温度(T/℃)或延长保温时间(t/min),SiCp/钎料界面的润湿性改善,6063Al基体/钎料间互扩散和溶解作用增强,接头连接质量逐渐提高。当T=590℃、t=30min时,接头抗剪强度达到112.6 MPa;当T=590℃、t=50min时,少量小尺寸SiCp因液态钎料排挤而分散于钎缝,因加工硬化而使接头强度递增7.3%。然而,当T≥595℃、t≥60min时,SiCp偏聚于钎缝,导致接头组织恶化,且剪切断裂以脆性断裂为主。综合考虑钎焊成本与接头强度使用要求,确定最佳钎焊工艺为590℃、30min。     

Brazing temperature-dependent interfacial reaction layer features between CBN and Cu-Sn-Ti active filler metal

CBN/Cu-Sn-Ti (CBN: cubic boron nitride) composites are prepared by active brazing sintering at 1123 K, 1173 K, 1223 K and 1273 K, respectively. The effects of brazing temperature on the wettability, interfacial characteristics, and elemental distribution variations are fully investigated. When the brazing temperature is below 1223 K, completely uncoated and/or partially coated CBN particles with sharp edges can still be observed, and the reaction layer, mainly composed of TiN and TiB2, appears to be thin and uneven. When the brazing temperature is 1223 K, all CBN particles are completely coated, suggesting that adequate wetting has taken place. Besides, as Ti diffuses thoroughly and enriches the interface, the reaction layer, filled primarily by TiN, TiB₂ and TiB, becomes thicker (about 1.30 μm), more uniform, stable and continuous. Further increasing the temperature to 1273 K is unnecessary or even harmful as the reaction layer thickness undergoes negligible change yet some tiny micro-cracks appear on the interface, which may likely deteriorate the grinding capability of the final brazing products.     

PMMA基纳米核-壳微粒改性R-PVC研究

探讨了经过特殊表征的有机刚性粒子—ＰＭＭＡ基核－壳型有机刚性粒子（ｃｏｒｅ－ｓｈｅｌｒｉｇｉｄｏｒｇａｎｉｃｆｉｌｅｒ）对Ｒ－ＰＶＣ／ＣＰＥ体系的增韧和增强作用及其对加工流变性的影响。研究发现,适当粒径的核－壳型粒子与Ｒ－ＰＶＣ／ＣＰＥ基体在适当配比下共混,常温（２３℃）下,可使ＰＶＣ／ＣＰＥ基体的冲击强度和断裂伸长率得到提高,断裂强度、屈服强度、硬度和加工流变性也有所改善,而在低温（－１０℃）下几乎没有增韧效果。     

乙烯裂解炉辐射段炉管Cr20Ni32Nb材料的焊接工艺

乙烯裂解炉炉管采用的高铬镍合金材料在焊接过程中易出现热裂纹的问题,针对该问题,在工程实际中对乙烯裂解炉辐射段炉管材料—Cr20Ni32Nb进行焊接性分析和焊接工艺评定,采用“超合金化”焊接材料,并制定合理的焊接工艺,成功地解决了Cr20Ni32Nb高铬镍材料离心铸造炉管的焊接热裂纹问题。     

Ti3Al对TiCu15Ni15钎料组织的影响

分别以0％，25％，50％，75％，100％比例的Ti3A1替换TiCu15Ni15中Ti，对所得的钎料进行组织形貌及成分分析。研究结果表明：钎料合金由先结晶低Cu，Ni含量相和后结晶的高Cu，Ni含量相组成，随TiaAl增加。低Cu，Ni含量相减少，高Cu，Ni含量相增加，同时由于Nb含量增加，背散射图像发生变化，先结晶相由灰色逐渐变为亮白色，后结晶相成分偏析增加，先结晶高Nb相为灰色，后结晶低Nb相为黑色，至5^#合金形态发生显著变化，灰色相由块团状变为短条或片状，其中央为白色边缘为灰色，这将引起性能变化。     

Microstructure and strength of brazed joints of Ti3Al-base alloy with NiCrSiB

Brazing of Ti₃Al alloys with the filler metal NiCrSiB was carried out at 1273–1373 K for 60–1800 s. The relationship of brazing parameters and shear strength of the joints was discussed, and the optimum brazing parameters were obtained. When products are brazed, the optimum brazing parameters are as follows: brazing temperature is 1323–1373 K, brazing time is 250–300 s. The maximum shear strength of the joint is 240–250 MPa. Three kinds of reaction products were observed to have formed during the brazing of Ti₃Al alloys with the filler metal NiCrSiB, namely, TiAl₃ (TiB₂) intermetallic compounds formed close to the Ti₃Al alloy. TiAl₃+AlNi₂Ti (TiB₂) intermetallic compounds layer formed between TiAl₃ (TiB₂) intermetallic compounds and the filler metal and a Ni[s,s] solid solution formed in the middle of the joint. The interfacial structure of brazed Ti₃Al alloy joints with the filler metal NiCrSiB is Ti₃Al/TiAl₃ (TiB₂)/TiAl₃+AlNi₂Ti (TiB₂)/Ni[s,s] solid solution/TiAl₃+AlNi₂Ti (TiB₂)/TiAl₃ (TiB₂)/Ti₃Al, and this structure will not change with brazing time once it forms. The formation of over many intermetallic compounds TiAl₃+AlNi₂Ti (TiB₂) results in embrittlement of the joint and poor joint properties. The thickness of TiAl₃+AlNi₂Ti (TiB₂) intermetallic compounds increases with brazing time according to a parabolic law. The activation energy Q and the growth velocity K₀ of the reaction layer TiAl₃+AlNi₂Ti (TiB₂) in the brazed joints of Ti₃Al alloys with the filler metal NiCrSiB are 349 kJ/mol and 24.02 mm²/s, respectively, and the growth formula was y²=24.04exp(−41977.39/T)t. Careful control of the growth of the reaction layer TiAl₃+AlNi₂Ti (TiB₂) can influence the final joint strength.