Aim To study the reason of the insensitiveness of Pearson product-momentcorrelation coefficient as a similarity measure and the method to improve its sensitivity. MethodsExperimental and simulated data sets were used....Aim To study the reason of the insensitiveness of Pearson product-momentcorrelation coefficient as a similarity measure and the method to improve its sensitivity. MethodsExperimental and simulated data sets were used. Results The distribution range of the data setsinfluences the sensitivity of Pearson product-moment correlation coefficient. Weighted Pearsonproduct-moment correlation coefficient is more sensitive when the range of the data set is large.Conclusion Weighted Pearson product-moment correlation coefficient is necessary when the range ofthe data set is large.展开更多
In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear chara...In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear characteristics was investigated. The friction-wearexperiment was carried out on the block-on-ring tribometer MM 200. The worn surfaces of the frictionpair consisting of the composite materials and grey cast iron HT 200 under dry sliding frictionwere examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) anddifferential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showedthat the friction coefficient and the wear loss of the composite material increase obviously withthe increase of cast iron debris content, but decrease obviously with the increase of graphitepowder content, and increase a little when the mass fraction of brass fiber was over 19 percent, andthe orientation of brass fiber has obvious influence on friction-wear property. When the massfraction of organic adhesion agent was about 10-11 percent, the composite materials have anexcellent friction-wear performance. The friction heat can pyrolyze organic ingredient in wornsurface layer.展开更多
The abrasive wear characteristics of Al_2O_3/PA1010 composite coatings on thesurface of quenched and low-temperature temper steel 45 were tested on the template abrasive weartesting machine and the same uncoated steel...The abrasive wear characteristics of Al_2O_3/PA1010 composite coatings on thesurface of quenched and low-temperature temper steel 45 were tested on the template abrasive weartesting machine and the same uncoated steel 45 was used as a reference material. Experimentalresults showed that the abrasive wear resistance of Al_2O_3/PA1010 composite coatings has a goodlinear relationship with the volume fraction of Al_2O_3 particles in Al_2O_3/PA1010 compositecoatings, and the linear correlative coefficient is 0.979. Under the experimental conditions, thesize of Al_2O_3 particles (40.5-161.0 μm) has little influence on the abrasive wear resistance ofAl_2O_3/PA1010 composite coatings. By treating the surface of Al_2O_3 particles with a suitablebonding agent, the distribution of Al_2O_3 particles in matrix PA1010 is more homogeneous and thebonding state between Al_2O_3 particles and matrix PA1010 is better. Therefore, the Al_2O_3particles in Al_2O_3/PA1010 composite coatings make the Al_2O_3/PA1010 composite coatings havebetter abrasive wear resistance than PA1010 coatings. The wear resistance of Al_2O_3/PA1010composite coatings is about 45% compared with that of steel 45.展开更多
SiC whiskers with 'rosary bead' morphology were synthesized using suitablesilicon source and carbon source through solid reaction at the temperature above 1537 K. Thediameter and length of the SiC whiskers wer...SiC whiskers with 'rosary bead' morphology were synthesized using suitablesilicon source and carbon source through solid reaction at the temperature above 1537 K. Thediameter and length of the SiC whiskers were about 0.1-1.0 μm and 20-100 μm, respectively. Thelargest diameter of their enlarged ends of the whiskers was about 0.2-1.0μm, and it gradually andsmoothly decreased to the size of the plain part of the whiskers. The results of X-ray diffractionanalysis show that the crystalline structure of the obtained SiC whiskers is β-SiC. It isconsidered that the SiC whiskers grow via a vapor-solid mechanism.展开更多
Abrasive wear characteristics of polyethylene, polystyrene,polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relativewear resistance coefficients of these thermoplastic polymers a...Abrasive wear characteristics of polyethylene, polystyrene,polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relativewear resistance coefficients of these thermoplastic polymers are 18%-35% (hardened and lowtemperature tempered steel 45 was used as a comparing material), and have a linear correlation withsquare roots of their cohesive energy densities. The coefficients of linear correlation is 0.949.Wear morphologies were observed by scanning electron microscope (SEM). Main wear mechanism of thethermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing andfatiguing for the soft and tough ones.展开更多
文摘Aim To study the reason of the insensitiveness of Pearson product-momentcorrelation coefficient as a similarity measure and the method to improve its sensitivity. MethodsExperimental and simulated data sets were used. Results The distribution range of the data setsinfluences the sensitivity of Pearson product-moment correlation coefficient. Weighted Pearsonproduct-moment correlation coefficient is more sensitive when the range of the data set is large.Conclusion Weighted Pearson product-moment correlation coefficient is necessary when the range ofthe data set is large.
文摘In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear characteristics was investigated. The friction-wearexperiment was carried out on the block-on-ring tribometer MM 200. The worn surfaces of the frictionpair consisting of the composite materials and grey cast iron HT 200 under dry sliding frictionwere examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) anddifferential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showedthat the friction coefficient and the wear loss of the composite material increase obviously withthe increase of cast iron debris content, but decrease obviously with the increase of graphitepowder content, and increase a little when the mass fraction of brass fiber was over 19 percent, andthe orientation of brass fiber has obvious influence on friction-wear property. When the massfraction of organic adhesion agent was about 10-11 percent, the composite materials have anexcellent friction-wear performance. The friction heat can pyrolyze organic ingredient in wornsurface layer.
文摘The abrasive wear characteristics of Al_2O_3/PA1010 composite coatings on thesurface of quenched and low-temperature temper steel 45 were tested on the template abrasive weartesting machine and the same uncoated steel 45 was used as a reference material. Experimentalresults showed that the abrasive wear resistance of Al_2O_3/PA1010 composite coatings has a goodlinear relationship with the volume fraction of Al_2O_3 particles in Al_2O_3/PA1010 compositecoatings, and the linear correlative coefficient is 0.979. Under the experimental conditions, thesize of Al_2O_3 particles (40.5-161.0 μm) has little influence on the abrasive wear resistance ofAl_2O_3/PA1010 composite coatings. By treating the surface of Al_2O_3 particles with a suitablebonding agent, the distribution of Al_2O_3 particles in matrix PA1010 is more homogeneous and thebonding state between Al_2O_3 particles and matrix PA1010 is better. Therefore, the Al_2O_3particles in Al_2O_3/PA1010 composite coatings make the Al_2O_3/PA1010 composite coatings havebetter abrasive wear resistance than PA1010 coatings. The wear resistance of Al_2O_3/PA1010composite coatings is about 45% compared with that of steel 45.
文摘SiC whiskers with 'rosary bead' morphology were synthesized using suitablesilicon source and carbon source through solid reaction at the temperature above 1537 K. Thediameter and length of the SiC whiskers were about 0.1-1.0 μm and 20-100 μm, respectively. Thelargest diameter of their enlarged ends of the whiskers was about 0.2-1.0μm, and it gradually andsmoothly decreased to the size of the plain part of the whiskers. The results of X-ray diffractionanalysis show that the crystalline structure of the obtained SiC whiskers is β-SiC. It isconsidered that the SiC whiskers grow via a vapor-solid mechanism.
文摘Abrasive wear characteristics of polyethylene, polystyrene,polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relativewear resistance coefficients of these thermoplastic polymers are 18%-35% (hardened and lowtemperature tempered steel 45 was used as a comparing material), and have a linear correlation withsquare roots of their cohesive energy densities. The coefficients of linear correlation is 0.949.Wear morphologies were observed by scanning electron microscope (SEM). Main wear mechanism of thethermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing andfatiguing for the soft and tough ones.
