Goal: Low wolfram-containing cutting composite was obtained by fusion of titanium carbonitride and high melting temperature binding metallic phase. Method: The composite was obtained via compaction and further sinteri...Goal: Low wolfram-containing cutting composite was obtained by fusion of titanium carbonitride and high melting temperature binding metallic phase. Method: The composite was obtained via compaction and further sintering in vacuum furnace at 1600°C under 10<sup>-3</sup> Pa pressure. Phase analysis was performed on X-ray apparatus “DRON-3”;microstructure was determined by electron microscope NANOLAB-7, microhardness by MUCKE-mark microhardness meter;relative resistance of cutters was evaluated at similar modes of cutting according to distances they passed;experiments were carried out on turning lathe. Results: Physical-mechanical characteristics of the obtained composite are: σ<sub>bend</sub>, = 1000 - 1150 MPa, σ<sub>bend1000</sub>°C = 600 MPa, HV = 14 GPa;HV<sub>1000</sub>°C = 6.5 GPa. High speeds of cutting and high temperatures resistance of cutters made by the obtained composites exceeds 1.5 - 2-folds that of cutters made of the known BK8 and KNT20 hard alloys. Conclusion: Its application is recommended in hot steel treatment by cutting, for removal of the so-called burrs, as well as in steel treatment by cutting during pure and semi-pure operations. It can also be used in jet engines, chemical industry apparatuses, electric-vacuum devices, in industry of responsible details of rockets, nuclear reactors, flying apparatuses.展开更多
Lightweight high-strength and tough composites have enormous potentials in a multitude of fields in-cluding biomaterials,sporting goods,aerospace and automobile industries.Herein,we present a strat-egy to develop a no...Lightweight high-strength and tough composites have enormous potentials in a multitude of fields in-cluding biomaterials,sporting goods,aerospace and automobile industries.Herein,we present a strat-egy to develop a novel bulk Al/SiC composite with a nacre/foam hybrid structure to combine excellent lightweight of foams with outstanding strength and toughness of nacre.To reduce the adverse effect of foam pores on mechanical properties,we further propose to strengthen the foams with 3D nanofiber networks,obtaining a nacre/nanofiber reinforced foam structure.Simultaneously,new particle-bubble co-assembly and selective infiltration technologies are proposed to prepare the novel nacre/foam and nacre/nanofiber reinforced foam structures.The nacre/nanofiber reinforced foam composite shows greater specific strength and toughness than the nacre/foam composite,conventional dense Al/SiC composites and many engineering materials.Our approach opens a promising new avenue for the structure design and manufacturing of lightweight,high-performance structural materials.展开更多
New Ag/Ti_2 SnC(Ag/TSC) composites with uniform microstructure were prepared by powder metallurgy. The superior wettability between Ag and Ti_2 SnC was confirmed with a contact angle of 14°. Arc erosion propertie...New Ag/Ti_2 SnC(Ag/TSC) composites with uniform microstructure were prepared by powder metallurgy. The superior wettability between Ag and Ti_2 SnC was confirmed with a contact angle of 14°. Arc erosion properties of Ag/10 wt%Ti_2 SnC(Ag/10 TSC) and Ag/20 wt%Ti_2 SnC(Ag/20 TSC) contacts were investigated under 400 V/100 A/AC-3 and compared with Ag/CdO contact.The Ag/10 TSC contact exhibited comparable arc erosion property to Ag/CdO contact. The fine arc erosion resistance was attributed to the good wettability between Ti_2 SnC and Ag,the good heat-conducting property of Ag/10 TSC, and the slight decomposition of Ti_2 SnC that absorbed part of electric arc energy. The excessive Ti_2 SnC significantly decreased the thermal conducting property of the Ag/20 TSC composite, resulting in the severe heat accumulation that decomposed Ti_2 SnC and deteriorated arc erosion property. The oxidation behavior of Ti_2 SnC under high electric arc temperature was also studied and then an arc erosion mechanism was proposed to get a comprehensive understanding on the arc erosion property of Ag/TSC composites.展开更多
文摘Goal: Low wolfram-containing cutting composite was obtained by fusion of titanium carbonitride and high melting temperature binding metallic phase. Method: The composite was obtained via compaction and further sintering in vacuum furnace at 1600°C under 10<sup>-3</sup> Pa pressure. Phase analysis was performed on X-ray apparatus “DRON-3”;microstructure was determined by electron microscope NANOLAB-7, microhardness by MUCKE-mark microhardness meter;relative resistance of cutters was evaluated at similar modes of cutting according to distances they passed;experiments were carried out on turning lathe. Results: Physical-mechanical characteristics of the obtained composite are: σ<sub>bend</sub>, = 1000 - 1150 MPa, σ<sub>bend1000</sub>°C = 600 MPa, HV = 14 GPa;HV<sub>1000</sub>°C = 6.5 GPa. High speeds of cutting and high temperatures resistance of cutters made by the obtained composites exceeds 1.5 - 2-folds that of cutters made of the known BK8 and KNT20 hard alloys. Conclusion: Its application is recommended in hot steel treatment by cutting, for removal of the so-called burrs, as well as in steel treatment by cutting during pure and semi-pure operations. It can also be used in jet engines, chemical industry apparatuses, electric-vacuum devices, in industry of responsible details of rockets, nuclear reactors, flying apparatuses.
基金financially supported by the National Key R&D Program of China(No.2018YFA0702800)the National Natural Sci-ence Foundation of China(No.51002019)the Fundamental Re-search Funds for the Central Universities(Nos.DUT21GF309 and DUT22LAB114).
文摘Lightweight high-strength and tough composites have enormous potentials in a multitude of fields in-cluding biomaterials,sporting goods,aerospace and automobile industries.Herein,we present a strat-egy to develop a novel bulk Al/SiC composite with a nacre/foam hybrid structure to combine excellent lightweight of foams with outstanding strength and toughness of nacre.To reduce the adverse effect of foam pores on mechanical properties,we further propose to strengthen the foams with 3D nanofiber networks,obtaining a nacre/nanofiber reinforced foam structure.Simultaneously,new particle-bubble co-assembly and selective infiltration technologies are proposed to prepare the novel nacre/foam and nacre/nanofiber reinforced foam structures.The nacre/nanofiber reinforced foam composite shows greater specific strength and toughness than the nacre/foam composite,conventional dense Al/SiC composites and many engineering materials.Our approach opens a promising new avenue for the structure design and manufacturing of lightweight,high-performance structural materials.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51731004, 51671054, and 51501038)the Fundamental Research Funds for the Central Universities in China (Grant Nos. 2242018K40108 and 2242018K40109) were highly appreciated
文摘New Ag/Ti_2 SnC(Ag/TSC) composites with uniform microstructure were prepared by powder metallurgy. The superior wettability between Ag and Ti_2 SnC was confirmed with a contact angle of 14°. Arc erosion properties of Ag/10 wt%Ti_2 SnC(Ag/10 TSC) and Ag/20 wt%Ti_2 SnC(Ag/20 TSC) contacts were investigated under 400 V/100 A/AC-3 and compared with Ag/CdO contact.The Ag/10 TSC contact exhibited comparable arc erosion property to Ag/CdO contact. The fine arc erosion resistance was attributed to the good wettability between Ti_2 SnC and Ag,the good heat-conducting property of Ag/10 TSC, and the slight decomposition of Ti_2 SnC that absorbed part of electric arc energy. The excessive Ti_2 SnC significantly decreased the thermal conducting property of the Ag/20 TSC composite, resulting in the severe heat accumulation that decomposed Ti_2 SnC and deteriorated arc erosion property. The oxidation behavior of Ti_2 SnC under high electric arc temperature was also studied and then an arc erosion mechanism was proposed to get a comprehensive understanding on the arc erosion property of Ag/TSC composites.