The mechanical properties of ozonized high density polyethylene(HDPE)blended with sericite-tridymite-cristobalite(STC)were studied in this paper.The experimental results show that some oxygen containing polar groups a...The mechanical properties of ozonized high density polyethylene(HDPE)blended with sericite-tridymite-cristobalite(STC)were studied in this paper.The experimental results show that some oxygen containing polar groups areintroduced on the molecular chain of HDPE through ozonization,the compatibility between HDPE and STC is thusimproved,the mechanical properties of the blend are markedly enhanced.Compared with untreated HDPE/STC(60/40)blend,the yield strength and notched impact strength of ozonized HDPE/STC(60/40)blend are increased from 27.0 MPa to29.5 MPa and from 2.8 kJ/m^2 to 13.3 kJ/m^2,respectively,the notched impact strength is close to that of HDPE(13.6 kJ/m^2),the yield strength is in excess of 3.9 MPa of that of HDPE.The yield strength and notched impact strength will be furtherincreased to 30.7 MPa and 32.4 kJ/m^2 in case the ozonized HDPE is blended with STC pretreated with silane coupling agent.展开更多
In this work, the influences of alumina addition on cristobalite crystallization and properties of injec- tion molded silica-based ceramic cores were investigated. X-ray diffraction （XRD） was used to characterize ph...In this work, the influences of alumina addition on cristobalite crystallization and properties of injec- tion molded silica-based ceramic cores were investigated. X-ray diffraction （XRD） was used to characterize phase transformations in the samples, and the XRD result indicated that the addition of alumina pro- moted crystallization of fused silica during sintering at 1180-1220 ℃ and thus increases the amount of cristobalite. The increased amount of cristobalite as well as alumina addition led to much more thermal dilation due to their higher coefficients of thermal expansion than that of fused silica. The flexural strengths at room temperature and 1500 ~C were tested, and it was shown that alumina addition could not affect room temperature strength, but decreased the flexural strength at 1500 ℃. In addition, deflection resis- tance during heating to high temperatures was investigated, and the result indicated that alumina addition speeded up high temperature softening of the samples. XRD and scanning electron microscopy equipped with energy dispersive spectrometry （SEMJEDS） analysis suggested that this softening behavior was related with viscous flow sintering which could be accelerated by the reaction of alumina and silica with a product of mullite.展开更多
Generally the gold investment material consists of cristobalite,quartz and plaster.The physical property of gold investment materials depends on its thermal expansion coefficients,compressive strength,and particles si...Generally the gold investment material consists of cristobalite,quartz and plaster.The physical property of gold investment materials depends on its thermal expansion coefficients,compressive strength,and particles size distribution.Since the thermal expansion coefficient of cristobalite and quartz are 2.6×10^-6/℃and 2.32×10^-6/℃respectively,the composition ratio of each components influence the thermal and physical properties of gold investment materials.For the clinical applications,it is necessary to improve the properties of gold investment materials such as homogeneous size distribution and thermal expansion coefficients.In the present study,effect of inorganic fillers such as cristobalite and quartz on gold alloy investment was investigated to improve the properties of it.The compressive strength and thermal expansion coefficients of the specimens were evaluated.The results showed that cristobalite and quartz were homogeneously distributed by milling. The optimum compressive strength was obtained at the ratio of 42：22 cristobalite and quartz,respectively.展开更多
Cristobalite SiO2 can be obtained from the fused silica ceramic waste of ploysilicon plant, due to the phase conversion of fused silica to cristobalite during the process of polysilicon ingot. Cristobalite powder mate...Cristobalite SiO2 can be obtained from the fused silica ceramic waste of ploysilicon plant, due to the phase conversion of fused silica to cristobalite during the process of polysilicon ingot. Cristobalite powder materials with high purity are manufactured by milling the discarded waste above. Thermal expansion rate of the cristobalite and gypsum bonding moulds were studied, which show that the thermal expansion of the cristobalite phase transition could effectively compensate for the shrinkage of the gypsum at the temperature between 200 ℃ and 400 ℃. Casting experiments with copper alloy show that the cristobalite can improve the thermal performance of moulds for precise casting of jewelry.展开更多
The thermal characteristic of cristobalite plays an important role in the application of casting industry. Because the phase transition of silica glass and cristobalite has low volume change, the block cristobalite ha...The thermal characteristic of cristobalite plays an important role in the application of casting industry. Because the phase transition of silica glass and cristobalite has low volume change, the block cristobalite had been manufactured by calcining fused silica ceramic, the XRD, SEM and thermal characteristics of the cristobalite had been tested. The result shows the formation of porous structure in the block cristobalite, and thermal expansion rate of the phase transition of β/αcristobalite reaches 1.5% at the temperature range of 250-290 ℃.展开更多
The effect of γ-ray irradiation on the mechanical properties of high densitypolyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The ex-perimental results show that γ-ray irradiation can ...The effect of γ-ray irradiation on the mechanical properties of high densitypolyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The ex-perimental results show that γ-ray irradiation can improve the affinity between HDPE andSTC, and the dispersion of STC in HDPE matrix. Compared with HDPE/STC (80/20)blend, the yield stress and impact strength of irradiated HDPE (10kGy)/STC (80/20) blendare increased from 22.8 MPa and 70J/m to 28.5 MPa and 144J/m. The yield stress andimpact strength of HDPE/irradiated HDPE/STC (48/32/20) are 27.8MPa and 210J/m,respectively.展开更多
The production processes for Si and FeSi have traditionally been considered slag-free.However,recent excavations have revealed significant accumulation of CaO–SiO_(2)–Al_(2)O_(3)slag within the furnaces.This accumul...The production processes for Si and FeSi have traditionally been considered slag-free.However,recent excavations have revealed significant accumulation of CaO–SiO_(2)–Al_(2)O_(3)slag within the furnaces.This accumulation can obstruct the flow of materials and gases,resulting in lower metal yield and higher energy consumption.The main objective of the current work is to enhance our understanding of slag formation during Si and FeSi production.We investigate slag formation through the dissolution of limestone and iron oxide in quartz and condensate,focusing on the reactions between these materials at a gram scale.Our findings indicate that most slag reaches equilibrium relatively quickly at temperatures starting from 1673 K.Notably,slag formation starts at lower temperature when the iron source is present (1573 K) compared to when only CaO is involved (1673 K).The minor elements tend to accumulate at quartz grain boundaries prior to slag formation.Furthermore,the slag produced from condensate contains less SiO_(2)than that generated from quartz with limestone.The type of quartz source and SiO_(2)phase appears to have little influence on slag formation.Good wettability is a significant factor in reaction between quartz and slag.FactSage calculations indicates that the viscosity of the slag ranges from 0.02 to 14.4 Pa·s under furnace conditions,comparable to the viscosity of honey or motor oil at room temperature.展开更多
By calcinatng conunerial silica at 1500 t or adding sodium oxalate and calcinating at 85Ot, α-cristobalite was obtained. The Raman and IR spectra of arnorphous silica and α-cristobalite were studied. The Raman and I...By calcinatng conunerial silica at 1500 t or adding sodium oxalate and calcinating at 85Ot, α-cristobalite was obtained. The Raman and IR spectra of arnorphous silica and α-cristobalite were studied. The Raman and IR spectra showed obvious changes. While amorphous silica transformed to α-cristobalite. The peak posihons and peak shape changed, and new vibration mode appeared in the crystal phase. For amorphous silica, the Raman spectrum has a broad band between 210-515 cm- 1 and two weak peaks at 793 and 966 cm -1. After phase tfansition, the broad band split into two strong peaks at 416 and 231 cm-1, and the positions of weak peaks changed. The IR spectrum of SiO2 has two strong peaks at about 1100 and 480 cm-1 and a weak peak at 800 cm-1. For α-cristobalite, a strong new peak appeared at 620 cm-1, and the adsorption at 800 cm-1 increased considerably. α-cristobalite also has two adsorption peaks in far-infrared.展开更多
基金This project was supported by the Special Funds for Major State Basic Research Projects of China(No.G1999064809).
文摘The mechanical properties of ozonized high density polyethylene(HDPE)blended with sericite-tridymite-cristobalite(STC)were studied in this paper.The experimental results show that some oxygen containing polar groups areintroduced on the molecular chain of HDPE through ozonization,the compatibility between HDPE and STC is thusimproved,the mechanical properties of the blend are markedly enhanced.Compared with untreated HDPE/STC(60/40)blend,the yield strength and notched impact strength of ozonized HDPE/STC(60/40)blend are increased from 27.0 MPa to29.5 MPa and from 2.8 kJ/m^2 to 13.3 kJ/m^2,respectively,the notched impact strength is close to that of HDPE(13.6 kJ/m^2),the yield strength is in excess of 3.9 MPa of that of HDPE.The yield strength and notched impact strength will be furtherincreased to 30.7 MPa and 32.4 kJ/m^2 in case the ozonized HDPE is blended with STC pretreated with silane coupling agent.
文摘In this work, the influences of alumina addition on cristobalite crystallization and properties of injec- tion molded silica-based ceramic cores were investigated. X-ray diffraction （XRD） was used to characterize phase transformations in the samples, and the XRD result indicated that the addition of alumina pro- moted crystallization of fused silica during sintering at 1180-1220 ℃ and thus increases the amount of cristobalite. The increased amount of cristobalite as well as alumina addition led to much more thermal dilation due to their higher coefficients of thermal expansion than that of fused silica. The flexural strengths at room temperature and 1500 ~C were tested, and it was shown that alumina addition could not affect room temperature strength, but decreased the flexural strength at 1500 ℃. In addition, deflection resis- tance during heating to high temperatures was investigated, and the result indicated that alumina addition speeded up high temperature softening of the samples. XRD and scanning electron microscopy equipped with energy dispersive spectrometry （SEMJEDS） analysis suggested that this softening behavior was related with viscous flow sintering which could be accelerated by the reaction of alumina and silica with a product of mullite.
文摘Generally the gold investment material consists of cristobalite,quartz and plaster.The physical property of gold investment materials depends on its thermal expansion coefficients,compressive strength,and particles size distribution.Since the thermal expansion coefficient of cristobalite and quartz are 2.6×10^-6/℃and 2.32×10^-6/℃respectively,the composition ratio of each components influence the thermal and physical properties of gold investment materials.For the clinical applications,it is necessary to improve the properties of gold investment materials such as homogeneous size distribution and thermal expansion coefficients.In the present study,effect of inorganic fillers such as cristobalite and quartz on gold alloy investment was investigated to improve the properties of it.The compressive strength and thermal expansion coefficients of the specimens were evaluated.The results showed that cristobalite and quartz were homogeneously distributed by milling. The optimum compressive strength was obtained at the ratio of 42：22 cristobalite and quartz,respectively.
文摘Cristobalite SiO2 can be obtained from the fused silica ceramic waste of ploysilicon plant, due to the phase conversion of fused silica to cristobalite during the process of polysilicon ingot. Cristobalite powder materials with high purity are manufactured by milling the discarded waste above. Thermal expansion rate of the cristobalite and gypsum bonding moulds were studied, which show that the thermal expansion of the cristobalite phase transition could effectively compensate for the shrinkage of the gypsum at the temperature between 200 ℃ and 400 ℃. Casting experiments with copper alloy show that the cristobalite can improve the thermal performance of moulds for precise casting of jewelry.
基金Project supported by the State Key Program of National Natural Science of China(No. 41130746)
文摘The thermal characteristic of cristobalite plays an important role in the application of casting industry. Because the phase transition of silica glass and cristobalite has low volume change, the block cristobalite had been manufactured by calcining fused silica ceramic, the XRD, SEM and thermal characteristics of the cristobalite had been tested. The result shows the formation of porous structure in the block cristobalite, and thermal expansion rate of the phase transition of β/αcristobalite reaches 1.5% at the temperature range of 250-290 ℃.
基金Project supported by the National Natural Science Foundation of China and Ford-China R & D Fund.
文摘The effect of γ-ray irradiation on the mechanical properties of high densitypolyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The ex-perimental results show that γ-ray irradiation can improve the affinity between HDPE andSTC, and the dispersion of STC in HDPE matrix. Compared with HDPE/STC (80/20)blend, the yield stress and impact strength of irradiated HDPE (10kGy)/STC (80/20) blendare increased from 22.8 MPa and 70J/m to 28.5 MPa and 144J/m. The yield stress andimpact strength of HDPE/irradiated HDPE/STC (48/32/20) are 27.8MPa and 210J/m,respectively.
基金financially supported by the Norwegian Ferroalloy Producers Research Association (FFF) and the Research Council of Norway through KSP project 326581 Recursive。
文摘The production processes for Si and FeSi have traditionally been considered slag-free.However,recent excavations have revealed significant accumulation of CaO–SiO_(2)–Al_(2)O_(3)slag within the furnaces.This accumulation can obstruct the flow of materials and gases,resulting in lower metal yield and higher energy consumption.The main objective of the current work is to enhance our understanding of slag formation during Si and FeSi production.We investigate slag formation through the dissolution of limestone and iron oxide in quartz and condensate,focusing on the reactions between these materials at a gram scale.Our findings indicate that most slag reaches equilibrium relatively quickly at temperatures starting from 1673 K.Notably,slag formation starts at lower temperature when the iron source is present (1573 K) compared to when only CaO is involved (1673 K).The minor elements tend to accumulate at quartz grain boundaries prior to slag formation.Furthermore,the slag produced from condensate contains less SiO_(2)than that generated from quartz with limestone.The type of quartz source and SiO_(2)phase appears to have little influence on slag formation.Good wettability is a significant factor in reaction between quartz and slag.FactSage calculations indicates that the viscosity of the slag ranges from 0.02 to 14.4 Pa·s under furnace conditions,comparable to the viscosity of honey or motor oil at room temperature.
文摘By calcinatng conunerial silica at 1500 t or adding sodium oxalate and calcinating at 85Ot, α-cristobalite was obtained. The Raman and IR spectra of arnorphous silica and α-cristobalite were studied. The Raman and IR spectra showed obvious changes. While amorphous silica transformed to α-cristobalite. The peak posihons and peak shape changed, and new vibration mode appeared in the crystal phase. For amorphous silica, the Raman spectrum has a broad band between 210-515 cm- 1 and two weak peaks at 793 and 966 cm -1. After phase tfansition, the broad band split into two strong peaks at 416 and 231 cm-1, and the positions of weak peaks changed. The IR spectrum of SiO2 has two strong peaks at about 1100 and 480 cm-1 and a weak peak at 800 cm-1. For α-cristobalite, a strong new peak appeared at 620 cm-1, and the adsorption at 800 cm-1 increased considerably. α-cristobalite also has two adsorption peaks in far-infrared.
