Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and...Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding technique.Additionally,the effect of Si on the glass forming ability(GFA)of the layers was understood.Results show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological properties.The hardness of the coating layer increases monotonically with the Si content.At the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent decrease.At x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in x.Conversely,with an increase in Si content,the wear volume loss initially decreases and then increases.At a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.展开更多
Well-sintered polycrystalline cubic boron nitride(PCBN)composites with different contents of cubic boron nitride(CBN) were obtained using Al and TiN as additives under pressure of 5.5 GPa and temperature of 1450 ℃.Th...Well-sintered polycrystalline cubic boron nitride(PCBN)composites with different contents of cubic boron nitride(CBN) were obtained using Al and TiN as additives under pressure of 5.5 GPa and temperature of 1450 ℃.The network structure of CBN grains and bonding materials was observed using scanning electron microscope(SEM).With the help of X-ray diffraction(XRD) analysis,TiB2 and AlN could be determined as main products and Al3 Ti also was detected in the Al-rich samples after sintering process.Furthermore,it was shown that Vickers hardness of composites was improved with the increase of CBN contents.However,the lifetime of PCBN composites was in negative correlation with the amount of CBN in turning GCr15 hardened steels,and the surface roughness of workpieces machined by these PCBN composites also showed the same trend.A series of cutting data confirmed that the low CBN content in PCBN composites could enhance the working durability and improve the surface quality in turning hardened steels.The present experiments also indicated that the lowest value of flank wear was not constant for different PCBN composites when they were used to machine several workpieces with different hardness.展开更多
为利用小麦粉(wheat flour,WF)改良大豆分离蛋白(soy protein isolate,SPI)膜的性质,利用发酵的中筋WF-SPI在pH为7、8、9下制备了膜,以及利用含有低筋、中筋、高筋、特高筋的WF通过发酵后在pH9下制备了WF-SPI膜。通过测定膜的微观结构...为利用小麦粉(wheat flour,WF)改良大豆分离蛋白(soy protein isolate,SPI)膜的性质,利用发酵的中筋WF-SPI在pH为7、8、9下制备了膜,以及利用含有低筋、中筋、高筋、特高筋的WF通过发酵后在pH9下制备了WF-SPI膜。通过测定膜的微观结构、傅里叶变换红外光谱、十二烷基硫酸钠-聚丙烯酰氨凝胶电泳、机械性能、水蒸气透过率和热稳定性,探究pH和WF筋度对发酵WF-SPI膜理化性质的影响。WF-SPI膜的表面结构伴随pH的增加逐渐光滑致密,且膜中的蛋白分子间相互作用逐渐增强。伴随pH的增加,WF-SPI膜的抗拉伸强度(tensile strength,TS)和玻璃化转变温度(glass transition temperature,T_(g))逐渐提高,而断裂伸长率(elongation at break,EAB)和水蒸气透过率(water vapor permeability,WVP)逐渐降低。特高筋WF中的蛋白结构没有完全展开无法与SPI发生充分的相互作用,结果导致特高筋WF-SPI膜中的蛋白质会聚集在膜的下表面并破坏其致密的网络结构。中筋WF-SPI膜的TS和T_(g)分别达到12.53 MPa和50.94℃的最高值,而其WVP、透明度值和溶解度均达到最低值。因此,中筋WF和SPI经过发酵后在pH9下制备的复合膜具有良好的理化性质,研究结果将为WF-SPI膜的研发提供新的思路。展开更多
文摘Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding technique.Additionally,the effect of Si on the glass forming ability(GFA)of the layers was understood.Results show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological properties.The hardness of the coating layer increases monotonically with the Si content.At the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent decrease.At x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in x.Conversely,with an increase in Si content,the wear volume loss initially decreases and then increases.At a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.
文摘Well-sintered polycrystalline cubic boron nitride(PCBN)composites with different contents of cubic boron nitride(CBN) were obtained using Al and TiN as additives under pressure of 5.5 GPa and temperature of 1450 ℃.The network structure of CBN grains and bonding materials was observed using scanning electron microscope(SEM).With the help of X-ray diffraction(XRD) analysis,TiB2 and AlN could be determined as main products and Al3 Ti also was detected in the Al-rich samples after sintering process.Furthermore,it was shown that Vickers hardness of composites was improved with the increase of CBN contents.However,the lifetime of PCBN composites was in negative correlation with the amount of CBN in turning GCr15 hardened steels,and the surface roughness of workpieces machined by these PCBN composites also showed the same trend.A series of cutting data confirmed that the low CBN content in PCBN composites could enhance the working durability and improve the surface quality in turning hardened steels.The present experiments also indicated that the lowest value of flank wear was not constant for different PCBN composites when they were used to machine several workpieces with different hardness.
