This paper describes an investigation of the effect of ZrO2 nanoparticles on the abrasive properties,crystalline texture developments,and tribocorrosion behavior of Ni-P nanostructured coatings.In the investigation,Ni...This paper describes an investigation of the effect of ZrO2 nanoparticles on the abrasive properties,crystalline texture developments,and tribocorrosion behavior of Ni-P nanostructured coatings.In the investigation,Ni-P and Ni-P-ZrO2 nanostructured coatings are deposited on St52 steel via the electroless method.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),cyclic-static polarization tests in 3.5wt%NaCl solution,the tribocorrosion test(by back-and-forth wear in electrochemical cell),and the microhardness test using the Vickers method were performed to characterize and analyze the deposited coatings.The results of this study showed that the addition of ZrO2 nanoparticles to the Ni-P electroless bath produced the following:a sharp increase in wear and hardness resistance,the change of the wear mechanism from sheet to adhesive mode,the reduction of pitting corrosion resistance,significant reduction in the tribocorrosion protective properties,change in the preferred orientation of the crystalline texture coating from(111)to(200),increase in the sedimentation rate during the deposit process,and a sharp increase in the thickness of the Ni-P nanostructured coatings.展开更多
A new type of high chromium cast iron(HCCI)was prepared,and its microstructure,mechanical properties,and abrasion resistance were investigated systematically.Results showed that after surface carburizing and chromizin...A new type of high chromium cast iron(HCCI)was prepared,and its microstructure,mechanical properties,and abrasion resistance were investigated systematically.Results showed that after surface carburizing and chromizing,the microstructure of HCCI mainly consists of martensite,boride(M_(2)B),and carbide(M_(7)C_(3)),accompanied with a large amount of secondary precipitations M_(23)C_(6).Moreover,the morphology and hardness of the carbide and boride in HCCI change little,while the volume fraction of carbide and boride increases from 16.23%to 23.16%.This effectively increases the surface hardness of HCCI from 64.53±0.50 HRC to 66.58±0.50 HRC,with the result that the surface of HCCI possesses a better abrasion resistance compared to the center position.Furthermore,the wear mechanism of HCCI changes from micro-plowing to micro-cutting with the increase of surface hardness.展开更多
WC-8wt.% Co cemented carbides with varied nano-Al 2 O 3 and nano-ZrO 2 contents were prepared respectively following conventional powder metallurgical procedures. Effects of nano-Al 2 O 3 and nano-ZrO 2 on the microst...WC-8wt.% Co cemented carbides with varied nano-Al 2 O 3 and nano-ZrO 2 contents were prepared respectively following conventional powder metallurgical procedures. Effects of nano-Al 2 O 3 and nano-ZrO 2 on the microstructure, behavior, and abrasive wear resistance were investigated. The result shows that a finer and more homogenous microstructure can be achieved by increasing nano-Al 2 O 3 , and increasing nano-ZrO 2 makes the microstructure more refined. Nano-Al 2 O 3 and nano-ZrO 2 could both help to give increased hardness. Transverse rupture strength is higher if the above nano-oxides are doped appropriately, whereas excess addition is deleterious. Abrasive wear resistance presents different variations with respect to increasing nano-Al 2 O 3 and nano-ZrO 2 . By contrast, increasing nano-ZrO 2 enhances the abrasive wear resistance more effectively than increasing nano-Al 2 O 3 . The influence of the two nano-oxides contents on the abrasive wear resistance does not almost vary with wear time, and the optimum addition level of nano-Al 2 O 3 in WC-8% Co cemented carbide is 0.3 wt.% from the stand of abrasive wear resistance. In addition, both of the nano-oxides can retard the increase of wear rate in long-term abrasive wear.展开更多
The bronze alloyed powder composite containing nanoparticles was developed by hot pressing.The effects of the content and granularity of graphite on hardness,machinability,bending strength,compression strength,and fri...The bronze alloyed powder composite containing nanoparticles was developed by hot pressing.The effects of the content and granularity of graphite on hardness,machinability,bending strength,compression strength,and friction and wear behavior of the composites were studied.The microstructures of the specimens were analyzed by SEM.The results showed that the graphites are distributed in net when nanographites are added,resulting in the decrease of mechanical properties and abrasive resistance.When the content of nanographite is 10%,the composite is brittle.The graphite is distributed in the form of block when micrographite is added,improving the mechanical properties and abrasive resistance.Wear track was studied by SEM.展开更多
The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant st...The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant steel. The three-body impact abrasive wear behavior was also analyzed. The results showed that two-step controlled rolling besides quenching at 880 ℃ and tempering at 170 ℃ could result in optimal mechanical property., the Brinell hardness, tensile strength, elongation and --40 ℃ impact toughness were 531, 1530 MPa, 11.8% and 58 J, re- spectively. The microstructure was of fine lath martensite with little retained austenite. Three-body impact abrasive wear results showed that wear mechanism was mainly of plastic deformation fatigue when the impact energy was 2 J, and the relative wear resistance was 1.04 times higher than that of the same grade compared steel under the same working condition. The optimal hardness and toughness match was the main reason of higher wear resistance.展开更多
提出了一种制备连续纳米纤维包芯纱的方法,利用接地平行铝片作为接收装置,使得纳米纤维平行地搭接在2块铝片之间,处于2块铝片中央的芯纱通过绕自身纱轴旋转,将取向的纳米纤维卷绕在其表面。研究了平行铝片间距、纺丝电压、纺丝距离以及...提出了一种制备连续纳米纤维包芯纱的方法,利用接地平行铝片作为接收装置,使得纳米纤维平行地搭接在2块铝片之间,处于2块铝片中央的芯纱通过绕自身纱轴旋转,将取向的纳米纤维卷绕在其表面。研究了平行铝片间距、纺丝电压、纺丝距离以及溶液流量对纳米纤维包芯纱包覆率及耐磨性的影响规律。结果表明,利用该方法制备的纳米纤维包芯纱包覆较为均匀,无露芯现象,并且芯纱表面纳米纤维直径分布均匀,排列整齐且具有良好的取向度。当平行铝片间距为2 cm,电压为17 k V,纺丝距离为14 cm,流量为1.0 m L/h时,电纺过程较稳定,包覆效果较好,包覆率最高可达41.9%,并且所得纳米纤维包芯纱的耐磨性与其包覆率成正相关关系,增磨率最大可达142.3%,同时其力学性能较原纱也有略微提高。展开更多
文摘This paper describes an investigation of the effect of ZrO2 nanoparticles on the abrasive properties,crystalline texture developments,and tribocorrosion behavior of Ni-P nanostructured coatings.In the investigation,Ni-P and Ni-P-ZrO2 nanostructured coatings are deposited on St52 steel via the electroless method.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),cyclic-static polarization tests in 3.5wt%NaCl solution,the tribocorrosion test(by back-and-forth wear in electrochemical cell),and the microhardness test using the Vickers method were performed to characterize and analyze the deposited coatings.The results of this study showed that the addition of ZrO2 nanoparticles to the Ni-P electroless bath produced the following:a sharp increase in wear and hardness resistance,the change of the wear mechanism from sheet to adhesive mode,the reduction of pitting corrosion resistance,significant reduction in the tribocorrosion protective properties,change in the preferred orientation of the crystalline texture coating from(111)to(200),increase in the sedimentation rate during the deposit process,and a sharp increase in the thickness of the Ni-P nanostructured coatings.
基金the National Key Research and Development Project of China(No.2017YFB0305100)the Science and Technology Project of Guangdong Province(No.2017B090903005)+3 种基金the National Natural Science Foundation of China(No.52005217)the Science and Technology Project of Guangzhou City(No.201806040006)the Basic and Applied Basic Research Fund Project of Guangdong Province(Nos.2021A1515010523 and 2020A1515110020)the Fundamental Scientific Research Business Expenses of Central Universities(No.21620344).
文摘A new type of high chromium cast iron(HCCI)was prepared,and its microstructure,mechanical properties,and abrasion resistance were investigated systematically.Results showed that after surface carburizing and chromizing,the microstructure of HCCI mainly consists of martensite,boride(M_(2)B),and carbide(M_(7)C_(3)),accompanied with a large amount of secondary precipitations M_(23)C_(6).Moreover,the morphology and hardness of the carbide and boride in HCCI change little,while the volume fraction of carbide and boride increases from 16.23%to 23.16%.This effectively increases the surface hardness of HCCI from 64.53±0.50 HRC to 66.58±0.50 HRC,with the result that the surface of HCCI possesses a better abrasion resistance compared to the center position.Furthermore,the wear mechanism of HCCI changes from micro-plowing to micro-cutting with the increase of surface hardness.
基金supported by the Science and Technology Projects of Sichuan Province, China (No. 2008GZ0179)
文摘WC-8wt.% Co cemented carbides with varied nano-Al 2 O 3 and nano-ZrO 2 contents were prepared respectively following conventional powder metallurgical procedures. Effects of nano-Al 2 O 3 and nano-ZrO 2 on the microstructure, behavior, and abrasive wear resistance were investigated. The result shows that a finer and more homogenous microstructure can be achieved by increasing nano-Al 2 O 3 , and increasing nano-ZrO 2 makes the microstructure more refined. Nano-Al 2 O 3 and nano-ZrO 2 could both help to give increased hardness. Transverse rupture strength is higher if the above nano-oxides are doped appropriately, whereas excess addition is deleterious. Abrasive wear resistance presents different variations with respect to increasing nano-Al 2 O 3 and nano-ZrO 2 . By contrast, increasing nano-ZrO 2 enhances the abrasive wear resistance more effectively than increasing nano-Al 2 O 3 . The influence of the two nano-oxides contents on the abrasive wear resistance does not almost vary with wear time, and the optimum addition level of nano-Al 2 O 3 in WC-8% Co cemented carbide is 0.3 wt.% from the stand of abrasive wear resistance. In addition, both of the nano-oxides can retard the increase of wear rate in long-term abrasive wear.
文摘The bronze alloyed powder composite containing nanoparticles was developed by hot pressing.The effects of the content and granularity of graphite on hardness,machinability,bending strength,compression strength,and friction and wear behavior of the composites were studied.The microstructures of the specimens were analyzed by SEM.The results showed that the graphites are distributed in net when nanographites are added,resulting in the decrease of mechanical properties and abrasive resistance.When the content of nanographite is 10%,the composite is brittle.The graphite is distributed in the form of block when micrographite is added,improving the mechanical properties and abrasive resistance.Wear track was studied by SEM.
基金Item Sponsored by National Basic Research Program of China(2010CB630801)
文摘The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant steel. The three-body impact abrasive wear behavior was also analyzed. The results showed that two-step controlled rolling besides quenching at 880 ℃ and tempering at 170 ℃ could result in optimal mechanical property., the Brinell hardness, tensile strength, elongation and --40 ℃ impact toughness were 531, 1530 MPa, 11.8% and 58 J, re- spectively. The microstructure was of fine lath martensite with little retained austenite. Three-body impact abrasive wear results showed that wear mechanism was mainly of plastic deformation fatigue when the impact energy was 2 J, and the relative wear resistance was 1.04 times higher than that of the same grade compared steel under the same working condition. The optimal hardness and toughness match was the main reason of higher wear resistance.
文摘提出了一种制备连续纳米纤维包芯纱的方法,利用接地平行铝片作为接收装置,使得纳米纤维平行地搭接在2块铝片之间,处于2块铝片中央的芯纱通过绕自身纱轴旋转,将取向的纳米纤维卷绕在其表面。研究了平行铝片间距、纺丝电压、纺丝距离以及溶液流量对纳米纤维包芯纱包覆率及耐磨性的影响规律。结果表明,利用该方法制备的纳米纤维包芯纱包覆较为均匀,无露芯现象,并且芯纱表面纳米纤维直径分布均匀,排列整齐且具有良好的取向度。当平行铝片间距为2 cm,电压为17 k V,纺丝距离为14 cm,流量为1.0 m L/h时,电纺过程较稳定,包覆效果较好,包覆率最高可达41.9%,并且所得纳米纤维包芯纱的耐磨性与其包覆率成正相关关系,增磨率最大可达142.3%,同时其力学性能较原纱也有略微提高。
