Ag对Sn-57Bi无铅钎料组织和性能的影响

研究了在Sn-57Bi近共晶合金的基础上加入少量的Ag后对Sn-57Bi钎焊料铸态组织、抗拉强度和Sn-57Bi／Cu焊接性能的影响。试验结果表明，ωAg=0．1％～1．0％可使合金的共晶组织变细，β-Sn枝晶相的尺寸变小，提高其抗拉强度；使Sn-57Bi／Cu接头的剪切强度有所提高。     

铝件产品的火焰钎焊的缺陷分析及结构设计改进

随着汽车工业的迅速发展,汽车空调也在飞速发展。在全球化的激烈竞争下,汽车空调产品在质量和成本上都更严格的要求。基于价格的因素,汽车空调的蒸发器和冷凝器原有的铜制品基本被铝制品所代替。由于材质的差异,导致该零部件在设计和制造中都出现了新的问题。本文在介绍铝件产品焊接的基本原理的基础上,针对汽车空调的蒸发器和冷凝器中出口管、进口管组件在焊接过程中的一般缺陷进行了总结和理论分析,并在此基础上提出了相应的结构设计和焊接工艺改进方法。该方法在运用于实际产品中获得了较好的应用效果,提高了产品的可靠性,降低了产品成本,提高了产品质量。     

A Ti–Zr–Cu–Ni–Co–Fe–Al–Sn amorphous filler metal for improving the strength of Ti–6Al–4V alloy brazing joint

Ti_(50)Zr_(27)Cu_8Ni_4Co_3Fe_2Al_3Sn_3(at%) amorphous filler metal with low Cu and Ni contents in a melt-spun ribbon form was developed for improving mechanical properties of Ti–6Al–4V alloy brazing joint through decreasing brittle intermetallics in the braze zone. Investigation on the crystallization behavior of the multicomponent Ti–Zr–Cu–Ni–Co–Fe–Al–Sn amorphous alloy indicates the high stability of the supercooled liquid against crystallization that favors the formation of amorphous structure. The Ti–6Al–4V joint brazed with this Ti-based amorphous filler metal with low total content of Cu and Ni at 1203K for 900s mainly consists of α-Ti, β-Ti,minor Ti–Zr-rich phase and only a small amount of Ti_3Cu intermetallics, leading to the high shear strength of the joint of about 460 MPa. Multicomponent composition design of amorphous alloys is an effective way of tailoring filler metals for improving the joint strength.     

Formation mechanism of interfacial microstructures and mechanical properties of Ti2AlNb/Ni-based superalloy joints brazed with NiCrFeSiB filler metal

Dissimilar brazing of Ti₂AlNb-based alloy and Ni-based wrought superalloy (GH536) was studied using NiCrFeSiB filler metal. The Ti₂AlNb/GH536 joints were analyzed by scanning electron microscope (SEM) equipped with an electron probe micro-analyzer (EPMA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The formation mechanism of interfacial microstructure and mechanical properties of Ti₂AlNb/GH536 joints were studied. The results indicated that Ti₂Ni(Al,Nb), AlNi₂Ti and TiB₂ reaction layers were formed in the joint adjacent to Ti₂AlNb base metal. These layers resulted in high micro-hardness and the weak link of the joint. γ solid solution was formed through isothermal solidification and β₁-Ni₃Si phase precipitated in the γ solid solution during cooling process. Ni₃B, β₁-Ni₃Si and CrB phases appeared in the centre of the joint. Blocky and needle-like borides formed within the diffusion affected zone of GH536 base alloy. The maximum tensile strength of Ti₂AlNb/GH536 joints reached 425 ?MPa ?at room temperature and the strength value of 373 ?MPa was maintained at 923 ?K.     

Microstructure and mechanical properties of the SiC/Zr4 joints brazed with TiZrNiCu filler for nuclear application

Si C ceramic has been successfully joined to Zr4 alloy using Ti Zr Ni Cu filler within the temperature range1173 K–1263 K and 15 min holding time. The morphology of the Si C/Zr4 joints was investigated by SEM, and the phases in the joints were characterized by XRD and TEM. The results indicated that part of the Zr4 substrate dissolved into the molten filler during the brazing process, contributed to the increasing Zr content and the formation of Zr[Ti] solid solution in the joints. In addition, β-Ti phase was discovered in the brazing seam. This might be attributed to the existence of β-Ti stable elements, Cu and Ni. The interface characterization showed that Si C reacted with filler alloy during the brazing process, formed a(Zr, Ti)C reaction layer on Si C surface and Zr2 Si compound near Si C substrate. Finally, the mechanical properties of the joints, evaluated by a shear strength test, reached a maximum of 95 MPa at the brazing temperature of 1203 K.     

基于VC的单个钎焊环剔除控制系统的设计

在传统的钎焊环检测分选系统中,由于钎焊环处于平铺片状排列在传送带上,剔除过程中采用的气嘴喷射方法会将许多合格环带出传送带,剔除效果不够理想。本文针对该问题,设计了利用小气缸作为机械手的剔除机构,提出一种利用VC和下位机PLC结合的剔除控制系统,完成了对单个缺陷钎焊环的剔除。通过试验证明:利用该剔除系统能够有效地减少了被吹落合格环的数量,提高了剔除的准确度和有效性。     

Microstructure evolution and mechanical properties of Ti_2AlNb/TiAl brazed joint using newly-developed Ti–Ni–Nb–Zr filler alloy

Joining of Ti_2AlNb alloy to TiAl intermetallics was conducted by the newly-developed Ti–Ni–Nb–Zr brazing filler alloy.The microstructure evolution of the joints was investigated by scanning electron microscope (SEM),energy dispersive spectrometer (EDS) and electron backscatter diffraction (EBSD).The macro-micro mechanical properties were studied by shear test and nano-indentation test.Typical interfacial microstructures across the brazing seam were Ti_2AlNb substrate,α_2-Ti_3Al+β-Ti,γ-TiAl+Ti_2Ni+TiNi+α_2-Ti_3Al,α_2-Ti_3Al+β-Ti,TiAl substrate.The Ti_2Ni phase were firstly dissolved in the joints brazed at 1000°C for 10 min and then precipitated after a prolonged holding time of 15 min.The nano-indentation test revealed that Ti_2Ni phase exhibited the highest hardness of 12.60 GPa.The joints brazed at 1000°C/15 min presented the maximum shear strength of271 MPa.The dissolution and precipitation behavior of Ti_2Ni phase was also discussed.     

Microstructure and mechanical properties of TiAl/TiAl joints brazed with a newly developed Ti–Ni–Nb–Zr quaternary filler alloy

A novel Ti–Ni–Nb–Zr quaternary filler alloy with the composition of Ti-(19～25)Ni-(15～25)(Nb ?+ ?Zr) (wt.%) was designed. The filler alloy was composed of (Ti,Nb)ss, (Ti,Zr,Nb)ss ?+ ?(Ti,Zr)₂Ni, α-Ti and Ti₂Ni phases. It was fabricated into filler foil with a thickness of about 45 ?μm by a rapid solidification technique. The results indicate that the liquidus temperature of the Ti–Ni–Nb–Zr brazing alloy was about 978 ^oC, and the brazing alloy presented excellent wettability on TiAl substrate. The TiAl joint mainly consisted of β/B2 phase, Ti₂Al, Ti₂AlNi and α₂-Ti₃Al phases. The diffusion of Al atom from base metal to brazed seam led to the formation of Ti₂Al and Ti₂AlNi. Considering that no previously references on XRD pattern of Ti₂AlNi compound can be found, Ti₂AlNi cast alloy specimen was specially prepared and XRD peaks were specially labeled. The micro-hardness and bending strength tests of the Ti₂AlNi phase were carried out, and the results were 761 HV and 192 ?MPa, respectively. The brazing parameters of 1010 ^oC/10 ?min offered the joint shear strength of 280 ?MPa at room temperature, and the joints exhibited tensile strength of 372 ?MPa at room temperature and 340 ?MPa at 750 ^oC, indicating that the newly developed filler alloy could offer a stable high-temperature strength.     

聚晶金刚石切削齿散热电阻钎焊工艺的研究

采用散热电阻钎焊工艺对聚晶金刚石切削齿进行钎焊，钎缝的抗剪强度达４１７．５ＭＰａ。复合片的磨耗比下降率小于１０％。采用表面测温实时监控技术，使复合片上金刚石层受热的温度低于７００℃。用复合片切削岩石，由此测定出复合片的耐磨性。这样增加了测试结果的可靠性。现场应用表明，用本工艺钎焊的聚晶金刚石切削齿制造的钻头质量稳定，基本无掉片现象。     

采煤机截齿钎焊工艺研究与分析

本文对采煤机截齿YG13C台金齿头钎焊用钎剂、钎料及钎焊后热处理工艺进行了研究与分析,对截齿钎焊工艺提出了改进意见。