Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the su...Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories： unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.展开更多
Steel micro fibers provide strengthening,toughening and durability improve-ment mechanisms in cementitious composites.However,there is not much data in the literature regarding how the extent of their effectiveness ch...Steel micro fibers provide strengthening,toughening and durability improve-ment mechanisms in cementitious composites.However,there is not much data in the literature regarding how the extent of their effectiveness changes depend-ing on the type of matrix being reinforced.For clarifying this point,the influ-ence of a constant volumetric ratio(1%)of 6 mm long steel micro fibers on the performance of 5 mortar mixtures was investigated and were prepared using plain,binary and ternary cementitious systems.A total of 10 mixtures were cast.The mineral admixtures used in the study include silica fume(SF),metakaolin(MK)and a Class C fly ash(FA).While the replacement levels of SF and MK were 10%by weight of the total mass of the binder,this ratio was chosen as 30%for FA.In addition to the behavior of the mixtures under compressive,flexural and impact loads,abrasion,water absorption,chloride ion penetration,freez-ing-thawing resistance and drying shrinkage characteristics of the mixtures were determined.Test results indicate that generally the refinement in the pore struc-ture of the matrix provided by mineral admixtures and the increase in resistance against growth and coalescence of micro-cracks provided by fibers produce a syn-ergistic effect and improve the investigated performances of the mixtures.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51375176)Guangdong Provincial Natural Science Foundation of China(Grant No.2014A030313264)Fundamental Research Funds for the Central Universities,SCUT,China(Grant No.2013ZZ017)
文摘Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories： unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.
文摘Steel micro fibers provide strengthening,toughening and durability improve-ment mechanisms in cementitious composites.However,there is not much data in the literature regarding how the extent of their effectiveness changes depend-ing on the type of matrix being reinforced.For clarifying this point,the influ-ence of a constant volumetric ratio(1%)of 6 mm long steel micro fibers on the performance of 5 mortar mixtures was investigated and were prepared using plain,binary and ternary cementitious systems.A total of 10 mixtures were cast.The mineral admixtures used in the study include silica fume(SF),metakaolin(MK)and a Class C fly ash(FA).While the replacement levels of SF and MK were 10%by weight of the total mass of the binder,this ratio was chosen as 30%for FA.In addition to the behavior of the mixtures under compressive,flexural and impact loads,abrasion,water absorption,chloride ion penetration,freez-ing-thawing resistance and drying shrinkage characteristics of the mixtures were determined.Test results indicate that generally the refinement in the pore struc-ture of the matrix provided by mineral admixtures and the increase in resistance against growth and coalescence of micro-cracks provided by fibers produce a syn-ergistic effect and improve the investigated performances of the mixtures.
