The fractal dimension（FD） of surfaces has been widely used to characterize the properties of materials.However,most of the previous researches were concentrated on the correlation between the FD of surfaces and mech...The fractal dimension（FD） of surfaces has been widely used to characterize the properties of materials.However,most of the previous researches were concentrated on the correlation between the FD of surfaces and mechanical properties of materials,such as impact energy and fracture toughness,etc.The aim of this paper is to characterize the spheroidization grade and strength of 15CrMo steel through determination of FD of cementite phase on the basis of two-dimension microstructural image.Two methods,namely slit-island method（SIM） and box-counting method（BCM）,are used to determine the value of FD.It is found that the FD value evaluated by using BCM is generally higher than that evaluated by SIM.This phenomenon may be due to the difference in the principles used in different methods.Whether SIM or BCM is used,the spheroidization grade in 15CrMo steel linearly increases with decreasing the value of FD.The relationship between the FD value,D,and spheroidization grade,Sg,can be approximately expressed as D≌-0.11Sg＋A,where A is a constant value which is depended on the evaluation method.Both the ultimate strength and the yielding strength of 15CrMo steel increase with increasing FD of cementite phase.There may be a common relationship between the FD of cementite phase and strength of 15CrMo steel.When the FD of cementite phase in 15CrMo steel is determined,the strength of this steel can be evaluated.The present paper can provide a novel method to evaluate the strength and spheroidization grade of carbon steel through determination of fractal dimension（FD） of cementite phase.展开更多
Zirconia/stainless steel (ZrO2/SUS316L) functionally graded materials (FGMs) were fabricated by tape casting and laminating. Microstructures of FGMs were observed by optical microscope. Fracture behavior of FGMs in di...Zirconia/stainless steel (ZrO2/SUS316L) functionally graded materials (FGMs) were fabricated by tape casting and laminating. Microstructures of FGMs were observed by optical microscope. Fracture behavior of FGMs in different loading modes and influences of different gradient changes on flexural strength were investigated. The results show that ZrO2/ SUS316L FGMs with graded components at interlayers are obtained after they are sintered in vacuum and pressureless condition at 1 350 ℃. TheⅠ?Ⅱ mixed mode crack creates in composite layer and grows to both sides zigzag while loading on ZrO2 layer. Flexural strengths are 496.4,421.7 and 387.5 MPa when gradient changes are 10%,15% and 20%,but flexural strengths of the corresponding fracture layers are 387.1,334.6 and 282.3 MPa since cracks of FGMs are affected by three-dimensional stress,respectively. The cracks are generated in ZrO2 layer and extend to SUS316L layer while loading is added on SUS316L layer,flexural strength does not change with the graded components and keeps consistent basically.展开更多
Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found tha...Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis （EPMA） verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.展开更多
This study considers P.O42.5 cement from different sources and evaluates the related surplus coefficient(defined as the proportionality factor linking the measured compressive strength value of the cement after 28 day...This study considers P.O42.5 cement from different sources and evaluates the related surplus coefficient(defined as the proportionality factor linking the measured compressive strength value of the cement after 28 days to the“standard”value of cement strength).The needed tests have been conducted using a mixer,a pressure testing machine,a flexural testing machine,a vibrating table a ramming rod,a feeder and a metal ruler.The average value of the measured cement strength surplus coefficient of cement produced by five distinct cement manufacturers has been found to be 1.16.These results can be used as the basis to reduce the production cost and improve the performance of commercial concrete.展开更多
针对水泥稳定级配碎石混合料配合设计方法的不足,引入混合料目标级配的概念,提出填充料、嵌挤料、骨架料等配合比设计专用名词。以广东省普遍应用的水泥稳定级配碎石基层混合料级配范围为基础,采用统计归纳的方法,建立9条运营良好的高...针对水泥稳定级配碎石混合料配合设计方法的不足,引入混合料目标级配的概念,提出填充料、嵌挤料、骨架料等配合比设计专用名词。以广东省普遍应用的水泥稳定级配碎石基层混合料级配范围为基础,采用统计归纳的方法,建立9条运营良好的高速公路花岗岩类混合料填充料、嵌挤料、骨架料等相关通过率与7 d无侧限强度关系,并拟合各强度影响因素与无侧限强度之间的关系(校正决定系数Adj R 2=0.9178),构建了花岗岩类水泥稳定级配碎石配合比设计方法。新的配合比设计方法解决了水泥稳定级配碎石基层混合料级配设计目标不明确、经验要求高、设计工作量大等问题,且可在设计初期预估无侧限强度。展开更多
基金supported by National Natural Science Foundations ofChina (Grant Nos. 50835003,50805047,10972078)National Hi-tech Research and Development Program of China (863 Program,Grant No.2009AA04Z421)
文摘The fractal dimension（FD） of surfaces has been widely used to characterize the properties of materials.However,most of the previous researches were concentrated on the correlation between the FD of surfaces and mechanical properties of materials,such as impact energy and fracture toughness,etc.The aim of this paper is to characterize the spheroidization grade and strength of 15CrMo steel through determination of FD of cementite phase on the basis of two-dimension microstructural image.Two methods,namely slit-island method（SIM） and box-counting method（BCM）,are used to determine the value of FD.It is found that the FD value evaluated by using BCM is generally higher than that evaluated by SIM.This phenomenon may be due to the difference in the principles used in different methods.Whether SIM or BCM is used,the spheroidization grade in 15CrMo steel linearly increases with decreasing the value of FD.The relationship between the FD value,D,and spheroidization grade,Sg,can be approximately expressed as D≌-0.11Sg＋A,where A is a constant value which is depended on the evaluation method.Both the ultimate strength and the yielding strength of 15CrMo steel increase with increasing FD of cementite phase.There may be a common relationship between the FD of cementite phase and strength of 15CrMo steel.When the FD of cementite phase in 15CrMo steel is determined,the strength of this steel can be evaluated.The present paper can provide a novel method to evaluate the strength and spheroidization grade of carbon steel through determination of fractal dimension（FD） of cementite phase.
基金Project (2007K06-13) supported by the Science and Technique Research and Development Program of Shaanxi Province, China
文摘Zirconia/stainless steel (ZrO2/SUS316L) functionally graded materials (FGMs) were fabricated by tape casting and laminating. Microstructures of FGMs were observed by optical microscope. Fracture behavior of FGMs in different loading modes and influences of different gradient changes on flexural strength were investigated. The results show that ZrO2/ SUS316L FGMs with graded components at interlayers are obtained after they are sintered in vacuum and pressureless condition at 1 350 ℃. TheⅠ?Ⅱ mixed mode crack creates in composite layer and grows to both sides zigzag while loading on ZrO2 layer. Flexural strengths are 496.4,421.7 and 387.5 MPa when gradient changes are 10%,15% and 20%,but flexural strengths of the corresponding fracture layers are 387.1,334.6 and 282.3 MPa since cracks of FGMs are affected by three-dimensional stress,respectively. The cracks are generated in ZrO2 layer and extend to SUS316L layer while loading is added on SUS316L layer,flexural strength does not change with the graded components and keeps consistent basically.
文摘Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis （EPMA） verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.
文摘This study considers P.O42.5 cement from different sources and evaluates the related surplus coefficient(defined as the proportionality factor linking the measured compressive strength value of the cement after 28 days to the“standard”value of cement strength).The needed tests have been conducted using a mixer,a pressure testing machine,a flexural testing machine,a vibrating table a ramming rod,a feeder and a metal ruler.The average value of the measured cement strength surplus coefficient of cement produced by five distinct cement manufacturers has been found to be 1.16.These results can be used as the basis to reduce the production cost and improve the performance of commercial concrete.
文摘针对水泥稳定级配碎石混合料配合设计方法的不足,引入混合料目标级配的概念,提出填充料、嵌挤料、骨架料等配合比设计专用名词。以广东省普遍应用的水泥稳定级配碎石基层混合料级配范围为基础,采用统计归纳的方法,建立9条运营良好的高速公路花岗岩类混合料填充料、嵌挤料、骨架料等相关通过率与7 d无侧限强度关系,并拟合各强度影响因素与无侧限强度之间的关系(校正决定系数Adj R 2=0.9178),构建了花岗岩类水泥稳定级配碎石配合比设计方法。新的配合比设计方法解决了水泥稳定级配碎石基层混合料级配设计目标不明确、经验要求高、设计工作量大等问题,且可在设计初期预估无侧限强度。
