Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechani...Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechanisms on the lower molding temperature limit and molding time in dental thermoforming. Ethylene vinyl acetate resin mouthguard sheet and two thermoforming machines;vacuum blower molding machine and vacuum ejector/pressure molding machine were used. The molding pressures for suction molding were −0.018 MPa for vacuum blower molding and −0.090 MPa for vacuum ejector molding, and for pressure molding was set to 0.090 MPa or 0.450 MPa. Based on the manufacturer’s standard molding temperature of 95˚C, the molding temperature was lowered in 2.5˚C increments to determine the lower molding temperature limit at which no molding defects occurred. In order to investigate the difference in molding time depending on the molding mechanism, the duration of molding pressure was adjusted in each molding machine, and the molding time required to obtain a sample without molding defects was measured. The molding time of each molding machine were compared using one-way analysis of variance. The lower molding temperature limit was 90.0˚C for the vacuum blower machine, 77.5˚C for the vacuum ejector machine, 77.5˚C for the pressure molding machine at 0.090 MPa, and 67.5˚C for the pressure molding machine at 0.45 MPa. The lower molding temperature limit was higher for lower absolute values of molding pressure. The molding time was shorter for pressure molding than for suction molding. Significant differences were observed between all conditions except between the pressure molding machine at 0.090 MPa and 0.45 MPa (P < 0.01). A comparison of the differences in lower molding temperature limit and molding time due to molding mechanisms in dental thermoforming revealed that the lower molding temperature limit depends on the molding pressure and that the molding time is longer for suction molding than for pressure molding.展开更多
Bulk amorphous crystal and microcrystal for Pr60Cu(20-x)Ni10Al10Fex (x = 0, 8, 15, 20) with the diameter ofΦ2 ~ 6 mm were manufactured by electric arc smelting, high frequency heating and copper mold upper suction ca...Bulk amorphous crystal and microcrystal for Pr60Cu(20-x)Ni10Al10Fex (x = 0, 8, 15, 20) with the diameter ofΦ2 ~ 6 mm were manufactured by electric arc smelting, high frequency heating and copper mold upper suction casting, and its structure was analyzed by X-ray diffract meter. It showed soft magnetic characteristic gradually when Fe content in it was up to 8% . The material was applied to magnetic-electric sensor as key component, output signal of which was measured with the change of Fe content. It shows that the signal changes from weak to strong with the increase of Fe content and presents the largest peak value when Fe is replaced by Cu completely.展开更多
The bulk nanocomposite magnets of Nd9Fes1-xTi4C2Nb4Bx （x= 11, 13, 15） in sheet form with the thickness of 0.7 mm were prepared by copper mold suction casting and subsequently annealing. The microstructure evolution ...The bulk nanocomposite magnets of Nd9Fes1-xTi4C2Nb4Bx （x= 11, 13, 15） in sheet form with the thickness of 0.7 mm were prepared by copper mold suction casting and subsequently annealing. The microstructure evolution and magnetic properties of bulk magnets were studied. It was shown that the as-cast microstmcture ofbtflk alloys were composed ofNdEFe14B, a-Fe, FeaB crystalline phases and an amorphous matrix, and that the glass formability of alloy was improved with increasing the B content. The DSC analysis showed that the as-cast bulk alloys had the crystallization behavior of a two-step process. After annealing at the temperatures which was 40453 K higher than their onset temperatures of the second exothermic peak, Nd9Fe81 xTi4C2Nb4Bx （x=11, 13, 15） bulk alloys obtained a finely mixed structure which were composed of Nd2Fe14B, a-Fe, Fe3B, （Nb,Ti）C crystalline phases and a residual amorphous phase, whose magnetic properties were significantly enhanced. For the bulk magnets of Nd9Fes1-xTi4CENb4Bx （x=11, 13, 15）, the optimal magnetic properties of Br=0.63 T, iHc= 155.1 kA/m, （BH）max= 18.73 kJ/m3 could be achieved when x= 13 after annealing at 983 K for 10 min.展开更多
文摘Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechanisms on the lower molding temperature limit and molding time in dental thermoforming. Ethylene vinyl acetate resin mouthguard sheet and two thermoforming machines;vacuum blower molding machine and vacuum ejector/pressure molding machine were used. The molding pressures for suction molding were −0.018 MPa for vacuum blower molding and −0.090 MPa for vacuum ejector molding, and for pressure molding was set to 0.090 MPa or 0.450 MPa. Based on the manufacturer’s standard molding temperature of 95˚C, the molding temperature was lowered in 2.5˚C increments to determine the lower molding temperature limit at which no molding defects occurred. In order to investigate the difference in molding time depending on the molding mechanism, the duration of molding pressure was adjusted in each molding machine, and the molding time required to obtain a sample without molding defects was measured. The molding time of each molding machine were compared using one-way analysis of variance. The lower molding temperature limit was 90.0˚C for the vacuum blower machine, 77.5˚C for the vacuum ejector machine, 77.5˚C for the pressure molding machine at 0.090 MPa, and 67.5˚C for the pressure molding machine at 0.45 MPa. The lower molding temperature limit was higher for lower absolute values of molding pressure. The molding time was shorter for pressure molding than for suction molding. Significant differences were observed between all conditions except between the pressure molding machine at 0.090 MPa and 0.45 MPa (P < 0.01). A comparison of the differences in lower molding temperature limit and molding time due to molding mechanisms in dental thermoforming revealed that the lower molding temperature limit depends on the molding pressure and that the molding time is longer for suction molding than for pressure molding.
文摘Bulk amorphous crystal and microcrystal for Pr60Cu(20-x)Ni10Al10Fex (x = 0, 8, 15, 20) with the diameter ofΦ2 ~ 6 mm were manufactured by electric arc smelting, high frequency heating and copper mold upper suction casting, and its structure was analyzed by X-ray diffract meter. It showed soft magnetic characteristic gradually when Fe content in it was up to 8% . The material was applied to magnetic-electric sensor as key component, output signal of which was measured with the change of Fe content. It shows that the signal changes from weak to strong with the increase of Fe content and presents the largest peak value when Fe is replaced by Cu completely.
基金Project supported by National Natural Science Foundation of China(51174121)Zhejiang Province Science and Technology Innovation Team of Key Projects(2010R50016-30)
文摘The bulk nanocomposite magnets of Nd9Fes1-xTi4C2Nb4Bx （x= 11, 13, 15） in sheet form with the thickness of 0.7 mm were prepared by copper mold suction casting and subsequently annealing. The microstructure evolution and magnetic properties of bulk magnets were studied. It was shown that the as-cast microstmcture ofbtflk alloys were composed ofNdEFe14B, a-Fe, FeaB crystalline phases and an amorphous matrix, and that the glass formability of alloy was improved with increasing the B content. The DSC analysis showed that the as-cast bulk alloys had the crystallization behavior of a two-step process. After annealing at the temperatures which was 40453 K higher than their onset temperatures of the second exothermic peak, Nd9Fe81 xTi4C2Nb4Bx （x=11, 13, 15） bulk alloys obtained a finely mixed structure which were composed of Nd2Fe14B, a-Fe, Fe3B, （Nb,Ti）C crystalline phases and a residual amorphous phase, whose magnetic properties were significantly enhanced. For the bulk magnets of Nd9Fes1-xTi4CENb4Bx （x=11, 13, 15）, the optimal magnetic properties of Br=0.63 T, iHc= 155.1 kA/m, （BH）max= 18.73 kJ/m3 could be achieved when x= 13 after annealing at 983 K for 10 min.
