浅析生烧石灰对电石电耗的影响

生石灰是制造电石的主要原料之一，其质量的好坏不仅影响到成品电石的质量，而且对电石电耗的影响也十分明显．生石灰中所含的生烧石灰对电耗的影响尤为严重。分析了山西三维集团2台电炉生烧率和电耗数据，发现生烧率每增加1％，实际电耗增加值在15kWh/t--30kWh/t，实践表明，以20kWh／t--30kWh／t比较适合。     

氧化钙对电石生产节能的影响

从电石生产工艺出发,分析了氧化钙(俗称白灰)的杂质、生过烧、粒度和粉末率对电石生产节能降耗的影响,并介绍了采取的相应措施。严把白灰原料质量关,科学合理调整配比,可有效提高电石产品质量,降低电石生产成本。     

Dynamic Compaction of Combustion-Synthesized Hafnium Carbide

The explosive-consolidation technique developed to fabricate combustion-synthesized titanium carbide and titanium diboride has been applied to hafnium carbide. Presently, the application of this technique results in a moderately dense HfC product. Sample confinement and configuration, explosive loading, and total heat available for the combustion-synthesis process were found to influence product characteristics. The key features of the process as well as some of the properties of the HfC ceramics produced are described.     

Molecular Simulation of Calcium Silicate Composites: Structure,Dynamics, and Mechanical Properties

Calcium silicate composite (CaO)_x(SiO₂)_1?x has significant applications in the bioactive materials in medical treatment and cementitious materials in construction engineering. In this study, to unravel the role of calcium atoms on the silicate composite, the molecular dynamics (MD) technique was used to simulate the structures, dynamics, and mechanical properties of (CaO)_x(SiO₂)_1?x systems, with x varying from 0 to 0.6. The Feuston–Garofalini model was employed to describe the interatomic interactions in the systems. Q species, the connectivity factor, shows that the increase in calcium content in the silicate composite can lead to the depolymerization of the silicate network. Due to the high diffusion rate, the presence of Ca atoms also weakens the stability of the chemical bonds in the system. With the increasing calcium content, the molecular structure of the silicate skeleton is transformed from an integrity network to separated short chains, which significantly decreases the stiffness and cohesive force of the calcium silicate composites. On the other hand, the uniaxial tension response of the calcium silicate composites suggests that at the postfailure stage, Ca atoms associate with the nonbridging oxygen atoms and the reconstructed Ca–O connection slows down the irreversible damage of the composite, hereby enhancing the plasticity.     

硅酸钙填充天然橡胶再生胶的性能研究

研究硅酸钙/炭黑并用比对天然橡胶(NR)再生胶性能的影响。结果表明:随着硅酸钙/炭黑并用比的增大,NR再生胶的焦烧时间逐步缩短,操作安全性降低,t90逐步缩短,硫化速率逐步提高;密度、邵尔A型硬度和拉断永久变形变化不大,拉伸强度和拉断伸长率明显提高,即硅酸钙对NR再生胶有明显的补强作用。     

Elastic Properties of Hafnium and Zirconium Oxides Stabilized with Praseodymium or Terbium Oxide

Elastic moduli of polycrystalline HfO₂ and ZrO₂ stabilized with 33 mol% Praseodymium oxide or terbium oxide were studied as functions of porosity and temperature. Thermal expansion was measured to 1200°C for each composition. The modulus-vs-porosity and thermal expansion curves were typical; however, modulus-vs-temperature relations were abnormally steep below 400°C, a phe nomenon observed previously for stabilized HfO₂ compositions. All compositions exhibited obvious stoichiometric changes resulting from oxidation-reduction annealing, but only the Tb₄O₇-stabilized ZrO₂ showed any significant effect of oxidation state on the modulus values; this effect was very pronounced.     

超细硅酸钙对磷酸钙骨水泥性能的影响

选择α-磷酸三钙(α-TCP)为基本原料,添加羟基磷灰石(HAP)、磷酸氢钙(DCPD)、碳酸钙(CaCO<,3>)、氧化钙(CaO)等其它辅料,添加不同量的超细无定形硅酸钙(CaSiO<,3>),研究超细无定形CaSiO<,3>的加入量对磷酸钙骨水泥性能的影响.对其基本性能进行了研究,并对固化骨水泥样品进行了Ringer's模拟液浸泡实验,对浸泡液pH值、样品抗压强度随浸泡时间变化进行了研究.实验结果表明:在磷酸钙骨水泥中添加超细无定形CaSiO<,3>,可以促进骨水泥的固化,提高其硬化物的抗压强度.当在所设计的骨水泥配方中添加5%的超细无定形CaSiO,时,骨水泥的性能达到最佳.其对应的初凝时间、终凝时间分别只有5.5 min和16.5min,当骨水泥在Ringer's溶液中浸泡两周后,抗压强度可达50.44 MPa,同时浸泡液的pH值变化幅度小,和起始pH值(pH=7.40)接近.     

Some Structural and Electrical Properties of Lithium Silicate Glasses

Dielectric measurements, analyzed in terms of the Maxwell-Wagner-Sillars theories of inhomogeneous dielectrics, have been used to investigate the phase-separation characteristics of various lithium silicate glasses. Such measurements are shown to provide evidence of the continuous or discontinuous nature of separated phases and to allow estimates of their shape factors and concentrations. The results indicate that dielectric measurements are particularly useful in following phase-separation processes in glasses from the initial to the final stages.     

Structural Properties of Calcium Silicate Pastes: II, Effect of Curing Temperature

The chemical and physical properties of C₃S pastes cured at 4°, 25°, and 65°C were investigated. The 65°C paste had lower H₂O surface area and larger capillary pore volume than the 25°C paste. The structure of the gel in the 4°C paste changes markedly with increased hydration. These changes were reflected in an increase in H₂O surface area, decrease in C/S ratio, and decrease in the diameter of the mesopores. The degree of silicate polymerization increased with time and temperature of curing. In addition, the 4°C paste had a significant amount of monomer in the gel, which polymerizes with time.     

Photoluminescence Properties of Zinc Oxide in Barium and Fluorine Silicate Glasses

Zinc oxide (ZnO) was embedded in barium and fluorine silicate glass matrices, and luminescence properties of as-prepared glass samples were studied. For the fluorine-free glasses, a blue emission was observed. With partial substitution of BaF₂ for BaO in glass compositions, emission spectra of glasses show an obvious blue shift to the near-UV region. For the BaO-free glasses, the dominant UV emission shifts to the near-band-edge exciton emission position of ZnO and also shows a red shift with increasing BaF₂. At the same time, a visible emission shoulder appears in the blue to green region and becomes weak with introduction of increasing BaF₂.     

硅酸钙对PBAT流变性能与发泡行为的影响

通过熔融共混法制备聚己二酸/对苯二甲酸丁二酯(PBAT)/硅酸钙复合材料,对复合材料的结晶行为、流变行为和发泡行为进行研究。结果表明,活性硅酸钙粉体的加入降低PBAT的分子链运动能力,导致绝对结晶度由15.17%降低至13.79%。此外,PBAT的熔体弹性和可发性随着硅酸钙加入而提高。发泡成型后,PBAT泡沫的泡孔密度和发泡倍率都随着硅酸钙含量增加出现上升趋势,加入质量分数4%的硅酸钙后,PBAT发泡材料的泡孔密度提高至5.93×10~7个/cm~3,发泡倍率达到15.26倍。硅酸钙对PBAT发泡材料的泡孔形态具有显著的调控作用。     

Structural and Mechanical Properties of Silicon Carbide Mixtures Based on Boroethyl Silicate Binders

The rheologic properties of silicon carbide plastic mixtures with varying contents, in both concentration and type, of molding binders are analyzed. Ranges of binder concentrations, optimum for semi-dry pressing technology, are specified.     

Preparation and Characterization of Submicron Hafnium Oxide

Submicron hafnium oxide powder prepared by hydrolytic decomposition of alkoxides was studied. The particle size range of this powder was 10 to 50 Å. Emission spectrographic analysis of the powder after it was calcined at 250°C for 0.5 h indicated a purity of >99.995%. Up to 320°C, the powder showed no crystallinity by X-ray analysis. The amorphous HfO₂ was isothermally aged at 5° to 10°C intervals between 200° and 500°C. X-ray diffraction patterns indicate a sharp transition from an amorphous state to the monoclinic phase at 325°C. High-temperature X-ray studies and DTA suggest nucleation and growth of small crystallites at 420°C leading to conversion to monoclinic HfO₂ at 480°C. BET surface area measurements and TGA of the powders were also conducted. A powder which transformed at 325°C to the monoclinic phase was isothermally aged below 325°C for 150 h without change.     

Structural Properties of Calcium Silicate Pastes: I, Effect of the Hydrating Compound

The chemical and physical properties of C₃S, β-C₂S, a C₃S/C₂S blend, and portland cement pastes cured at 25°C were investigated. The H₂O specific surface areas of the calcium silicate samples follow a common linear relation when plotted against a CIS ratio. The β-C₂S had higher capillary porosity and N2 surface area, resulting from increased mesopore volume at the expense of micropores. All calcium silicate pastes had similar polysilicate content vs time curves, indicating an aging process which is not sensitive to the starting composition of the hydrating calcium silicate. The polysilicate content of portland cement was much lower than that of the corresponding calcium silicate pastes. Strength-capillary porosity relations for the various systems are discussed.     

Industrial Diamond Substitutes: I, Physical and X-Ray Study of Hafnium Carbide

A study of hard materials in an effort to find possible substitutes for industrial diamonds led to research on hafnium carbide. This compound was prepared from a mixture of hafnium dioxide and lampblack in a carbon resistance furnace by solid-state reaction or from a melt. Some factors affecting the combined carbon content of the re- action products were qualitatively evaluated. A hafnium carbide prepared from a melt at a temperature slightly above 2800°C. with no holding time had a combined carbon content within 98% of the theoretical value. A curve was obtained by plotting combined carbon against cubic unit- cell dimension (a₀) for the hafnium carbide- "hafnium monoxide" solid solution series. Extrapolation gave 4.641 ± 0.001 a.u. for the cell edge of hafnium carbide of theoretical composition; a₀ was observed as high as 4.640 a.u. Density values within 99% of theoretical were obtained. Knoop microindentation hardness measurements with both dry and oil-immersion objectives indicated a hardness in the silicon carbide range. Owing to its high cost and relatively low hard- ness, hafnium carbide is presently not considered to be a promising substitute for industrial diamonds.     

硬硅钙石型硅酸钙对涂料绝热性能的影响

对动态水热法合成的硬硅钙石型硅酸钙进行了XRD、SEM表征,将所制得的硬硅钙石型硅酸钙作填料配制成硅酸盐绝热涂料,与不掺硬硅钙石的涂料在绝热性能方面进行了比较,发现硬硅钙石对涂料的绝热性能有显著的影响,并进一步按照国标GB/T 10297—1998的要求用热线法测得所配制涂料试样的热导率约为0.05 W/(m.K)。     

氧化钙固硫性能的研究

研究了氧化钙（CaO）在煤燃烧过程中的固硫性能，讨论了燃煤的硫含量，温度、钙硫比以及添加二氧化铈(CeO2）对CaO固硫性能的影响，实验结果表明，随着煤中硫含量的增加，CaO的固硫率增大；CaO的固硫率在最佳固硫温度以下随温度升高而增大，超过最佳固硫温度则随温度升高而下降；同时还发现钙硫比在1：1以上时，CaO的固硫效果比较好，最佳固硫温度约为900℃；当温度为900℃且钙硫比为1：1时，CaO的最大固硫率可达到68％；CeO2的添加，可使最大固硫率提高约10％。     

Mechanical Properties of High Density Polyethylene/Modified Calcium Silicate Composites

High density polyethylene (HDPE)/calcium silicate (CS) composites containing vinyltriethoxysilane treated calcium silicate contents varying from 0–10 phr were prepared by injection molding. Thus obtained HDPE/CS composites were characterized by the thermal analyses. The mechanical properties were evaluated. It was found that the incorporation of the calcium silicate into high density polyethylene resulted in a slight increase in the yield stress (6.85–11.76 %) as well as tensile strength (7.02–12.84 %). However, the elongation at yield and the elongation at break decreased by 9.23–24.87 % and by 11.03–60.73 %, respectively, with the increasing calcium silicate content. The vinyltriethoxysilane modified CS exhibited the dispersibility in HDPE matrix arising from the compatibility between high density polyethylene matrix and the disperse phase (treated calcium silicate particles) which led to the effect on the mechanical properties of the composites. It could be concluded that the modified calcium silicate played a role in reinforcing the mechanical properties into the high density polyethylene.