铝钢异种金属压力钎焊研究

作为汽车轻量化材料中最主要的两类材料,高强度钢板和铝合金组成的钢-铝一体化车身成为轻量化的发展技术路线.本试验用Cu作为中间层,通过压力钎焊对工业纯铝和Q235低碳钢进行了连接.试验研究了工艺参数对接头组织和性能的影响,分析了其接头的显微组织、力学性能和元素分布,确定出了合适的连接工艺参数,并对各连接界面形貌进行了分析.研究表明,室温下接头的拉伸强度和弯曲强度等于或超过基体,焊缝与母材之间没有形成脆性相.     

PDC钻头用浸渍钎料性能研究

依据Cu,Zn,Ni,Mn,Sn,Fe,Si和稀土元素在钎料中的作用,开发出一种新型钎料JZ-2。通过对其熔化温度、润湿性能、力学性能与传统钎料对比分析,得出该钎料在以上性能方面全面超过传统的516钎料和CuNi36Mn10钎料,具体表现为:该钎料熔化温度较低,约在1 144～1 173℃;对WC的润湿长度较高,为402 mm;抗拉强度高,为704 MPa,并且塑性加工性能好;浸焊件的抗弯强度高,约为689 N/mm2;JZ-2浸焊件冲击韧性高,约为4.22 J/cm2。     

A novel Ag–CuAlO2 sealant for reactive air brazing of 3YSZ and AISI 310S

Based on reactive air brazing (RAB), we designed a new type of sealant (Ag–xCuAlO₂) for joining 3 mol.% yttria-stabilized zirconia (YSZ) ceramics and AISI 310S stainless steel. The CuAlO₂ content affected the wettability of the sealant on the YSZ surface, and the joints had a high shear strength when Ag–2 wt.%CuAlO₂, which had a small contact angle on the YSZ substrate, was used as the sealant. In addition, the thickness of the oxide layer was reduced compared to that for the Ag–CuO sealant. The effects of the processing parameters on the microstructure and shear strength of the joints were investigated, and the as-brazed joints reached their highest shear strength (93.7 MPa) when brazed at 1040 °C for 30 min. After high-temperature oxidation at 800 °C for 200 h, the shear strength of the joints remained at 50 MPa, and no apparent change in the microstructure was observed, proving that the joints possessed excellent oxidation resistance.     

Wettability and interfacial reaction mechanism between Ag–Cu alloy and Si3N4 ceramics in air atmosphere

The wetting behaviour and interfacial reaction mechanism between Ag–Cu alloy fillers (with varying copper contents) and Si₃N₄ ceramics using reactive air brazing at 970 °C were systematically investigated. As the copper content increased, the contact angles of the Ag–Cu filler on the Si₃N₄ ceramics decreased. A violent boiling-like interfacial reaction was observed during the experiment, and mass spectrometry analysis identified the gaseous products as N₂, NO and NO₂. The solid products SiO₂ and Cu–O formed at the interface, and the interfacial reactions improved the wettability of the Ag–Cu filler on the Si₃N₄ ceramics. Owing to buoyancy and the pushing of the gases, the interfacial products floated to the surface of the filler and their distribution increased along with the increasing copper content. Two different microstructures were formed at the interface near the triple line. Thick and thin SiO₂ layers were respectively formed on the triple line interface of the fillers with low (Ag–3Cu/Ag–5Cu) and high (Ag–6.6Cu/Ag–16Cu) copper content. The interfacial bonding zones formed in Ag–5Cu, Ag–6.6Cu, and Ag–16Cu samples indicated that the corresponding Ag–Cu fillers were effectively brazed with the Si₃N₄ ceramics.     

DZ38G高温合金扩散钎焊微观结构分析

在真空环境下采用Ni-Si-B中间层,扩散钎焊DZ38G高温合金,扩散连接温度为1050℃,扩散连接时间为30～70min,焊后均质化保温温度为1050℃,保温时间为300 min.研究了接头的微观结构.研究表明:等温凝固完成前,接头主要有四种不同的相构成:初始共晶的γ固溶体、Ni基硼化物、共晶的γ固溶体和母材金属;在1050℃下,扩散钎焊时间70 min以上,可完成等温凝固.     

Brazing of UNS S32101 and UNS S32304 lean duplex stainless steels and UNS S32750 super duplex with AWS A5.3 BNi-7 (Ni–Cr–P) filler metal

Summary

Weld metals solidified in the ferritic-austenitic solidification mode (FA mode) have dual phases of ferrite and austenite in their as-solidified condition, where ferrite exhibits different morphologies depending on the chemical composition and welding conditions. This paper describes an investigation of the effect of the solidification and transformation sequence on the formation of final ferrite morphologies. Austenite is formed through either a eutectic reaction or peritectic reaction at the dendrite boundaries after the primary formation of ferrite. During the eutectic formation of austenite, the <100>_δ direction of the primary ferrite and the <100>_γ direction of the eutectic austenite are parallel to each other and lie along the growth direction of the primary dendrites. However, any specific lattice plane relationship between the two phases is not identified. During cooling after solidification, the austenite extends into the primary ferrite via solid-state transformation, and the final morphology of the ferrite is vermicular without any coherent orientation relationship between the primary ferrite and eutectic austenite. During peritectic formation of austenite, the Kurdjumov-Sachs orientation relationship is established between the primary ferrite and peritectic austenite, and the <100>_γ direction of the peritectic austenite is not parallel to the growth direction of the primary dendrites. During cooling after solidification, the primary ferrite transforms into austenite, and the final morphology of the ferrite is lathy, since the primary ferrite and peritectic austenite have a favourable coherent orientation.     

Densification and joining of a (HfTaZrNbTi)C high-entropy ceramic by hot pressing

A bulk (Hf_0.2Ta_0.2Zr_0.2Nb_0.2Ti_0.2)C high-entropy ceramic (HEC) with a high density was prepared by hot pressing (HP), and through a robust joining technique, large-sized piece was fabricated. A hot-pressed carbide HEC with a single-phase and homogeneous composition was obtained at the sintering temperatures from 1800 to 1950 °C for 30 min under a pressure of 30 MPa. The influence of sintering temperature on the mechanical properties of the HEC was investigated, and the flexural and compressive strengths were reported. Additionally, the feasibility of active brazing of this HEC was studied and solid joints with high shear strength were obtained by atomic diffusion and chemical reaction at the interface, providing a key approach to fabricate complex components of HECs.     

TC4钛合金钎焊接头的组织与性能

采用Ti-37.5Zr-15Cu-10Ni钎料对TC4钛合金进行了钎焊,钎焊温度为900 ℃,保温时间分别为30、60和90 min。结果表明,在900 ℃时该钎料可润湿TC4母材,润湿角平均值为16.7°。保温时间为90 min时,钎焊界面中心处钎料元素已扩散得较充分,与钎料合金成分相比,Zr元素由37.5%降低至1.79%,Cu和Ni元素分别由15%和10%降低至1.66%和1.64%。TC4钛合金钎焊试样的室温抗拉强度平均值为1007.6 MPa,多数试样断于母材,属于微孔聚合机制导致的断裂失效。     

面向制冷行业在线应用的铝铝感应钎焊

铝管由于其熔点低,在焊接的过程中很容易烧破,致使管壁减薄或管路泄漏。所以,制冷行业的铝铝管路基本采用洛克环进行连接,洛克环连接的成本较高,并且洛克环在本质上不属于焊接,在安装工艺不成熟时也会存在较大比例的焊漏率;铝铝感应钎焊在工艺成熟的前提下可以实现铝管的低成本连接,并且焊接效果稳定,降低焊漏率。针对铝铝管的感应钎焊进行研究,并探究铝铝感应钎焊的在线应用条件,推动感应钎焊在制冷行业铝铝管路连接中的应用和发展。     

银钎焊剂水溶法改性处理工艺的优化

采用水溶法改性工艺制备银钎剂，正交试验表明，烘干时间对钎剂性能的影响最大，其次是成分配比及烘干温度．在配方为42％KF 23％KBF4 35％B2O3，烘干时间为45min，烘干温度为350℃时，制备的银钎剂质量稳定且焊接效果良好．