As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of P...As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of PCD inserts.In addition,the former cutting paths are strainghter with less chipping on the edge.However,there have been no report on CVD diamond films that were used as a roller scriber for splitting large glass panels.Our research demonstrated that the CVD diamond film could concentrate the energy in a smaller area(about 1/4),so the glass compressed by the tip of the diamond film was under a larger tensile stress in perpendicular to the direction of compression.The tensile stress then initiated the microcracks that were more in line with the direction of the compression. The reason that CVD diamond film could concentrate the compressive stress was due to its 100%diamond content.The high diamond content could allow the tip to be polished sharper.In contrast,the PCD cutting tip contained micro grains of cobalt that were softer than glass.As a result,the compressional stress was spreading out due to the larger area of contact.Consequently,the microcracks initiated at the PCD tip were random and they might not propagate along the direction of cutting.展开更多
The pseudo-equilibrium phase diagram and continuous cooling transformation diagram of an N-containing 8％ Cr roller steel were investigated by using thermodynamic calculation,differential scanning calorimetry,Ⅹ-ray d...The pseudo-equilibrium phase diagram and continuous cooling transformation diagram of an N-containing 8％ Cr roller steel were investigated by using thermodynamic calculation,differential scanning calorimetry,Ⅹ-ray diffraction,expansion method,and so on.Under equilibrium conditions,the main carbonitrides are MX,M7C3,and M23C6 types.The measured Ac1,Ac3,start temperature of martensitic transformation,and M7C3 transformation temperatures are 811,855,324,and 1100 ℃,respectively.Bainite appears at cooling rates ranging from 0.5 to 5 ℃/s and ferrite forms at grain boundaries at a cooling rate lower than 0.5 ℃/s.Finally,the effects of adding N and lowering the C content on workability and mechanical properties of common 8％Cr steel were discussed.展开更多
文摘As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of PCD inserts.In addition,the former cutting paths are strainghter with less chipping on the edge.However,there have been no report on CVD diamond films that were used as a roller scriber for splitting large glass panels.Our research demonstrated that the CVD diamond film could concentrate the energy in a smaller area(about 1/4),so the glass compressed by the tip of the diamond film was under a larger tensile stress in perpendicular to the direction of compression.The tensile stress then initiated the microcracks that were more in line with the direction of the compression. The reason that CVD diamond film could concentrate the compressive stress was due to its 100%diamond content.The high diamond content could allow the tip to be polished sharper.In contrast,the PCD cutting tip contained micro grains of cobalt that were softer than glass.As a result,the compressional stress was spreading out due to the larger area of contact.Consequently,the microcracks initiated at the PCD tip were random and they might not propagate along the direction of cutting.
基金Sponsored by the Natural Science Foundation of Hebei Province for Distinguished Young Scholars(Grant No.E2011203131)the Natural Science Foundation-Steel and Iron Foundation of Hebei Province(Grant No.E2013203110)
文摘The pseudo-equilibrium phase diagram and continuous cooling transformation diagram of an N-containing 8％ Cr roller steel were investigated by using thermodynamic calculation,differential scanning calorimetry,Ⅹ-ray diffraction,expansion method,and so on.Under equilibrium conditions,the main carbonitrides are MX,M7C3,and M23C6 types.The measured Ac1,Ac3,start temperature of martensitic transformation,and M7C3 transformation temperatures are 811,855,324,and 1100 ℃,respectively.Bainite appears at cooling rates ranging from 0.5 to 5 ℃/s and ferrite forms at grain boundaries at a cooling rate lower than 0.5 ℃/s.Finally,the effects of adding N and lowering the C content on workability and mechanical properties of common 8％Cr steel were discussed.
