There are two ways to join ceramics to metals: brazing and bonding. However, brazing processes are time-comsuming and energy-comsuming and is limited by the low working temperature. Generally speaking, bonding, or spe...There are two ways to join ceramics to metals: brazing and bonding. However, brazing processes are time-comsuming and energy-comsuming and is limited by the low working temperature. Generally speaking, bonding, or specifically, Diffusion Bonding performs better than brazing. Besides diffusion bonding, a more specialized technique is Field Assisted Diffusion Bonding (FADB).展开更多
SiCp/2024 matrix composites reinforced with SiC particles and 2219 aluminum alloy were joined via centered electron beam welding and deflection beam welding,respectively,and the microstructures and mechanical properti...SiCp/2024 matrix composites reinforced with SiC particles and 2219 aluminum alloy were joined via centered electron beam welding and deflection beam welding,respectively,and the microstructures and mechanical properties of these joints were investigated.The results revealed that SiC particle segregation was more likely during centered electron beam welding(than during deflection beam welding),and strong interface reactions led to the formation of many Al4C3 brittle intermetallic compounds.Moreover,the tensile strength of the joints was 104 MPa.The interface reaction was restrained via deflection electron beam welding,and only a few Al4C3 intermetallic compounds formed at the top of the joint and heat affected zone of SiCp/Al.Quasi-cleavage fracture occurred at the interface reaction layer of the base metal.Both methods yielded a hardness transition zone near the SiCp/2024 fusion zone,and the brittle intermetallic Al4C3compounds formed in this zone resulted in high hardness.展开更多
An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical ...An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.展开更多
Nano-ceramic particles are generally difficult to add into molten metal because of poor wettability. Nano-SiC_Particles reinforced A356 aluminum alloy composites were prepared by a new complex process, i.e., a molten-...Nano-ceramic particles are generally difficult to add into molten metal because of poor wettability. Nano-SiC_Particles reinforced A356 aluminum alloy composites were prepared by a new complex process, i.e., a molten-metal process combined with high energy ball milling and ultrasonic vibration methods. The nano particles were β-SiC_P with an average diameter of 40 nm, and pre-oxidized at about 850 °C to form an oxide layer with a thickness of approximately 3 nm. The mm-sized composite granules containing nano-SiC_P were fi rstly produced by milling the mixture of oxidized nano-SiC_P and pure Al powders, and then were remelted in the matrix-metal melt with mechanical stirring and treated by ultrasonic vibration to prepare the composite. SEM analysis results show that the nano-SiC_P articles are distributed uniformly in the matrix and no serious agglomeration is observed. The tensile strength and elongation of the composite with 2 wt.% nano-SiC_P in as-cast state are 226 MPa and 5.5%, improved by 20% and 44%, respectively, compared with the A356 alloy.展开更多
A new composite material consisting of lxxx aluminum alloy and 7xxx aluminum alloy was produced by semi-continuous casting. Macrostructure, microstructure, composition distribution and hardness distribution of composi...A new composite material consisting of lxxx aluminum alloy and 7xxx aluminum alloy was produced by semi-continuous casting. Macrostructure, microstructure, composition distribution and hardness distribution of composite interface were analyzed. Macrostructure shows that composite interface is planar and clean with little evidence of porosity; microstructure shows that composite interface is a kind of metallurgical bonding; composition and hardness distributions have a good corresponding relationship. At the same time, the mechanical property of composite interface was measured, the tensile strength is 71 MPa, the shearing strength is 62 MPa and the bending strength is 142.5 MPa, which can also show that composite interface is a kind of metallurgical bonding. Temperature distribution of composite interface was obtained by measuring temperatures near composite interface in lxxx aluminum alloy.展开更多
文摘There are two ways to join ceramics to metals: brazing and bonding. However, brazing processes are time-comsuming and energy-comsuming and is limited by the low working temperature. Generally speaking, bonding, or specifically, Diffusion Bonding performs better than brazing. Besides diffusion bonding, a more specialized technique is Field Assisted Diffusion Bonding (FADB).
基金Project was supported by the National Nature Science Foundation of China(51375115).
文摘SiCp/2024 matrix composites reinforced with SiC particles and 2219 aluminum alloy were joined via centered electron beam welding and deflection beam welding,respectively,and the microstructures and mechanical properties of these joints were investigated.The results revealed that SiC particle segregation was more likely during centered electron beam welding(than during deflection beam welding),and strong interface reactions led to the formation of many Al4C3 brittle intermetallic compounds.Moreover,the tensile strength of the joints was 104 MPa.The interface reaction was restrained via deflection electron beam welding,and only a few Al4C3 intermetallic compounds formed at the top of the joint and heat affected zone of SiCp/Al.Quasi-cleavage fracture occurred at the interface reaction layer of the base metal.Both methods yielded a hardness transition zone near the SiCp/2024 fusion zone,and the brittle intermetallic Al4C3compounds formed in this zone resulted in high hardness.
基金financially supported by the National Natural Science Foundation of China (No. 51272208)the Program for New Century Excellent Talents in University (NCET–12–0454)the Program for Young Excellent Talents in Shaanxi Province, China (2013KJXX–50)
文摘An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.
基金financially supported by the National Natural Science Foundation of China(No.51574129)Technological Innovation Special Project of Hubei Province(No.2017AAA110)
文摘Nano-ceramic particles are generally difficult to add into molten metal because of poor wettability. Nano-SiC_Particles reinforced A356 aluminum alloy composites were prepared by a new complex process, i.e., a molten-metal process combined with high energy ball milling and ultrasonic vibration methods. The nano particles were β-SiC_P with an average diameter of 40 nm, and pre-oxidized at about 850 °C to form an oxide layer with a thickness of approximately 3 nm. The mm-sized composite granules containing nano-SiC_P were fi rstly produced by milling the mixture of oxidized nano-SiC_P and pure Al powders, and then were remelted in the matrix-metal melt with mechanical stirring and treated by ultrasonic vibration to prepare the composite. SEM analysis results show that the nano-SiC_P articles are distributed uniformly in the matrix and no serious agglomeration is observed. The tensile strength and elongation of the composite with 2 wt.% nano-SiC_P in as-cast state are 226 MPa and 5.5%, improved by 20% and 44%, respectively, compared with the A356 alloy.
基金supported by Major State Basic Research Project of China (GrantNo.2005CB623707)
文摘A new composite material consisting of lxxx aluminum alloy and 7xxx aluminum alloy was produced by semi-continuous casting. Macrostructure, microstructure, composition distribution and hardness distribution of composite interface were analyzed. Macrostructure shows that composite interface is planar and clean with little evidence of porosity; microstructure shows that composite interface is a kind of metallurgical bonding; composition and hardness distributions have a good corresponding relationship. At the same time, the mechanical property of composite interface was measured, the tensile strength is 71 MPa, the shearing strength is 62 MPa and the bending strength is 142.5 MPa, which can also show that composite interface is a kind of metallurgical bonding. Temperature distribution of composite interface was obtained by measuring temperatures near composite interface in lxxx aluminum alloy.
