The transient liquid phase diffusion bonding of Si 3N 4 ceramics with Ti/Ni/Ti and Al/Ti/Al multiple interlayers was performed. The formation of intermetallic compounds in situ and their effects on the joints streng...The transient liquid phase diffusion bonding of Si 3N 4 ceramics with Ti/Ni/Ti and Al/Ti/Al multiple interlayers was performed. The formation of intermetallic compounds in situ and their effects on the joints strengths were investigated. The Ti/Ni/Ti interlayers produce NiTi and Ni 3Ti layers with considerable room temperature ductility and high elevated temperature strength to strengthen the bonding zone metals and the joints. The joints with 142 MPa shear strength at room temperature and 88 MPa shear strength at 800 ℃ are achieved under appropriate parameters, respectively. Al/Ti/Al interlayers transform into a special bonding zone metal with a large amount of Al 3Ti particles and a small amount of Al based solid solution, and in this case, the joints are strengthened significantly. Their strengths at room temperature and 600 ℃ reach 90 MPa and 30 MPa, respectively.展开更多
The preforms with high SiC volume fraction （〉50%） were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of SiC preforms were investigated, a...The preforms with high SiC volume fraction （〉50%） were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of SiC preforms were investigated, and the bonding mechanism among SiC particulates in preforms was also discussed. Results show that, after heating to 1 100 ~C and holding for 2 h, a uniform and interconnected structure in the SiC preforms can be obtained by using starch, stearic acid, and graphite respectively as the pore-forming agents, which benefits the subsequent infiltration by the molten metals. More neck-like-jointing among SiC particulate by using graphite as the pore-forming agent improves the dimensional accuracy and compressive strength of the preform. Besides, the properties of the preforms by the binder bonding are better than those by the oxidation bonding, which is mainly because the mixed neck-like-jointing and binder at high temperature provide effective bonding together.展开更多
Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is invest...Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.展开更多
The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation o...The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strain rate of 4.52×10^(-5) s^(-1) and the same temperature,and it was found that the elongation value in- creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al- loys were bonded by diffusion bonding technology and good joints were created,the simulated specimens were performed by SPF/DB process.展开更多
The effect of main technological parameters of diffusion bonding for titanium alloy, such as temperature,pressure and time,on joint strength was studied. A threedimensional curved surface among'joint strength and ...The effect of main technological parameters of diffusion bonding for titanium alloy, such as temperature,pressure and time,on joint strength was studied. A threedimensional curved surface among'joint strength and temperature,pressure,time was drawn. It can be used for selecting reasonable technological parameters.In order to have an overall understanding of the effeCt of technological parameters on the quality of bonded interfaces,the observation of fracture appearance by SEM was also carried out.展开更多
The forming condition of coal and coaly organic matter is analyzed. The dynamics of hydrocarbon generation of coal and coaly organic matter is discussed. It has been pointed out that the temperature is the main predom...The forming condition of coal and coaly organic matter is analyzed. The dynamics of hydrocarbon generation of coal and coaly organic matter is discussed. It has been pointed out that the temperature is the main predominant factor for the hydrocarbon generation of coal; chemical effect of structural pressing and shearing force accelerates the evolution of hydrocarbon derived from coal, and is the prerequisite for the hydrocarbons to be expelled from coal. The existence of atoms of N, S, O etc. is the prerequisite for forming the hydrocarbons at early evolution stage. The importance of NSO compounds in the evolution of hydrocarbon generation has been emphasized.展开更多
文摘The transient liquid phase diffusion bonding of Si 3N 4 ceramics with Ti/Ni/Ti and Al/Ti/Al multiple interlayers was performed. The formation of intermetallic compounds in situ and their effects on the joints strengths were investigated. The Ti/Ni/Ti interlayers produce NiTi and Ni 3Ti layers with considerable room temperature ductility and high elevated temperature strength to strengthen the bonding zone metals and the joints. The joints with 142 MPa shear strength at room temperature and 88 MPa shear strength at 800 ℃ are achieved under appropriate parameters, respectively. Al/Ti/Al interlayers transform into a special bonding zone metal with a large amount of Al 3Ti particles and a small amount of Al based solid solution, and in this case, the joints are strengthened significantly. Their strengths at room temperature and 600 ℃ reach 90 MPa and 30 MPa, respectively.
基金Funded by the National Natural Science Foundation of China(No.51166011)Aviation Science Foundation(No.2012ZF56024)Key Laboratory for Microstructural Control of Metallic Materials of Jiangxi Province(Nanchang Hangkong University)(No.JW201423003)
文摘The preforms with high SiC volume fraction （〉50%） were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of SiC preforms were investigated, and the bonding mechanism among SiC particulates in preforms was also discussed. Results show that, after heating to 1 100 ~C and holding for 2 h, a uniform and interconnected structure in the SiC preforms can be obtained by using starch, stearic acid, and graphite respectively as the pore-forming agents, which benefits the subsequent infiltration by the molten metals. More neck-like-jointing among SiC particulate by using graphite as the pore-forming agent improves the dimensional accuracy and compressive strength of the preform. Besides, the properties of the preforms by the binder bonding are better than those by the oxidation bonding, which is mainly because the mixed neck-like-jointing and binder at high temperature provide effective bonding together.
文摘Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.
文摘The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strain rate of 4.52×10^(-5) s^(-1) and the same temperature,and it was found that the elongation value in- creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al- loys were bonded by diffusion bonding technology and good joints were created,the simulated specimens were performed by SPF/DB process.
文摘The effect of main technological parameters of diffusion bonding for titanium alloy, such as temperature,pressure and time,on joint strength was studied. A threedimensional curved surface among'joint strength and temperature,pressure,time was drawn. It can be used for selecting reasonable technological parameters.In order to have an overall understanding of the effeCt of technological parameters on the quality of bonded interfaces,the observation of fracture appearance by SEM was also carried out.
文摘The forming condition of coal and coaly organic matter is analyzed. The dynamics of hydrocarbon generation of coal and coaly organic matter is discussed. It has been pointed out that the temperature is the main predominant factor for the hydrocarbon generation of coal; chemical effect of structural pressing and shearing force accelerates the evolution of hydrocarbon derived from coal, and is the prerequisite for the hydrocarbons to be expelled from coal. The existence of atoms of N, S, O etc. is the prerequisite for forming the hydrocarbons at early evolution stage. The importance of NSO compounds in the evolution of hydrocarbon generation has been emphasized.
