Aluminum-silicon （Al-Si） alloy is very difficult to machine and diamond tools are considered by far the best choice for the machining of these materials. Experimental results in the machining of the Al-Si alloy with...Aluminum-silicon （Al-Si） alloy is very difficult to machine and diamond tools are considered by far the best choice for the machining of these materials. Experimental results in the machining of the Al-Si alloy with diamond coated inserts are presented. Considering the fact that high adhesive strength and fine surface morphology play an importance role in the applications of chemical vapor deposition （CVD） diamond films, multilayer technique combining the hot filament CVD （HFCVD） method is proposed, by which multilayer diamond-coating on silicon nitride inserts is obtained, microcrystalline diamond （MCD）/ nanocrystalline diamond （NCD） film. Also, the conventional monolayer NCD and MCD coated inserts are produced for comparison. The as-deposited diamond films are characterized by field emission scanning electron microscopy （FE-SEM） and Raman spectrum. All the CVD diamond coated inserts and uncoated insert endure the aluminum-silicon alloy turning to estimate their cutting performances. Among all the tested inserts, the MCD/NCD coated insert exhibits the perfect behavior as tool wear due to its very low flank wear and no diamond peeling.展开更多
Fe/Si3N4 composite powder was synthesized by the heterogeneous precipitation-thermal reduction process,and then pressed into flakes under a pressure of 10 MPa.Flakes were sintered by pressureless and hot-pressing at 1...Fe/Si3N4 composite powder was synthesized by the heterogeneous precipitation-thermal reduction process,and then pressed into flakes under a pressure of 10 MPa.Flakes were sintered by pressureless and hot-pressing at 1 600℃under 0.1 MPa N2. The chemical composition,phases and microstructure of composite powder and sintered flakes were investigated by energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy (TEM).The results show that the structure of composite powders is Si3N4 coated by nano Fe.The crystal phases of sintered flakes by pressureless are Fe(Si)compound,SiC and Si3N4.The crystal phases of the sintered samples by hot-pressing are Fe,Fe(Si) compound and Si3N4.It is found that crystal phases flakes obtained by pressureless and hot-pressing are very different.展开更多
基金National Key Research and Development Program of China(2016YFB0700202)National Natural Science Foundation of China(51872310)Chinese Academy of Science(QYEDY-SSW-JSC031)
基金Project(50975177)supported by the National Natural Science Foundation of China
文摘Aluminum-silicon （Al-Si） alloy is very difficult to machine and diamond tools are considered by far the best choice for the machining of these materials. Experimental results in the machining of the Al-Si alloy with diamond coated inserts are presented. Considering the fact that high adhesive strength and fine surface morphology play an importance role in the applications of chemical vapor deposition （CVD） diamond films, multilayer technique combining the hot filament CVD （HFCVD） method is proposed, by which multilayer diamond-coating on silicon nitride inserts is obtained, microcrystalline diamond （MCD）/ nanocrystalline diamond （NCD） film. Also, the conventional monolayer NCD and MCD coated inserts are produced for comparison. The as-deposited diamond films are characterized by field emission scanning electron microscopy （FE-SEM） and Raman spectrum. All the CVD diamond coated inserts and uncoated insert endure the aluminum-silicon alloy turning to estimate their cutting performances. Among all the tested inserts, the MCD/NCD coated insert exhibits the perfect behavior as tool wear due to its very low flank wear and no diamond peeling.
基金Project(50804016)supported by the National Natural Science Foundation of China
文摘Fe/Si3N4 composite powder was synthesized by the heterogeneous precipitation-thermal reduction process,and then pressed into flakes under a pressure of 10 MPa.Flakes were sintered by pressureless and hot-pressing at 1 600℃under 0.1 MPa N2. The chemical composition,phases and microstructure of composite powder and sintered flakes were investigated by energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy (TEM).The results show that the structure of composite powders is Si3N4 coated by nano Fe.The crystal phases of sintered flakes by pressureless are Fe(Si)compound,SiC and Si3N4.The crystal phases of the sintered samples by hot-pressing are Fe,Fe(Si) compound and Si3N4.It is found that crystal phases flakes obtained by pressureless and hot-pressing are very different.
