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1.
Al2O3- C specimens were prepared using fused corundum and flake graphite as starting materials,SiC as antioxidant,and phenolic resin as binder to research their corrosion resistance to oolitic-hematite reduction melt. The tests of slag penetration and corrosion were carried out by static crucible method. The corrosion resistance was presented by the corrosion area and penetration depth. The corroded specimens were investigated by XRD,SEM and EDS. The results show that:(1) the corrosion resistance of Al2O3- C materials to oolitic-hematite reduction melt is improved obviously by the addition of SiC;(2) with the rising of reduction temperature and the prolonging of reduction duration,the corrosion area and penetration depth both increase rapidly;(3) the corrosion mechanism of the oolitic-hematite reduction melt can be described as that the melt reacts with Al2O3- C materials forming some low melting compounds such as CaO·Al2O3·2SiO2,CaO·2Al2O3and Fe2SiO4. 相似文献
2.
Li Maoqiang 《中国耐火材料》2014,(1):11-18
In order to understand the failure mechanism of magnesia-alumina spinel crown of glass melters,a discussion on the stability of Mg-Al-spinel crown of glass melters was given in this paper.The discussion focused on the weight balance in the crown arch made of spinel or silica bricks,the creep of spinel crown bricks at high temperatures,the thermal stress distribution in crown bricks as well as at brick joints,and the displacement behavior of crown arch during heat-up of glass melter.It is believed that the tangential stress in spinel crown is much higher than that in silica crown due to the large differenee in their densities,and that the thermal stresses in the crown brick result in opening of a part of the brickto-brick joints at the cold side of the crown,and increase of the tangential stress needed for balancing the weight of the crown.Both defect migration in lattice or along grain boundary and viscous flow in glass phase at grain boundary contribute to the creep of crown bricks at high temperatures.The creep of the matrix of spinel brick is more significant than that of coarse grains because impurities,such as silica and calcia,are concentrated in it.For keeping the crown stable during heat-up period it is important to adjust properly the horizontal positions of each skew brick as temperature increasing based on correctly evaluating the thermal expansion according to the thermal expansion coefficient of the crown brick. 相似文献
3.
Rizwan Safdar Abdul Aziz Omar Lukman B. Ismail Arhama Bari Bhajan Lal 《中国化学工程学报》2015,23(11):1811-1818
The density, viscosity and refractive index of aqueous solutions of tetrabutylammonium hydroxide (TBAOH), pi-perazine (PZ) and their aqueous blends are determined at several temperatures (303.15 to 333.15 K). All these measured physicochemical properties decreases with an increase in temperature. The density data is used to cal-culate the coefficient of thermal expansion and excess molar volume of al aqueous binary and ternary solutions. The coefficient of thermal expansion increases with increase in temperatures and concentrations. The negativity of excess molar volume for al the aqueous solution decreased with increase in temperature. Each physical prop-erty is correlated with temperature by least square method and the corresponding coefficients for each property are presented. The prediction values from correlations for the physical properties are in good agreement with the experimental values. 相似文献
4.
Muhammad Shuaib Shaikh Azmi Mohd Shariff Mohd Azmi Bustam Ghulam Murshid 《中国化学工程学报》2015,23(3):536-540
The physicochemical properties, including the density, viscosity, and refractive index of aqueous solutions of sodium glycinate as a solvent for CO2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K. The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol·L?1. The coefficients of thermal expansion values were estimated from measured density data. It was found that, the densities, viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature, whereas with increasing sodium glycinate concentration in the solution, all three properties increase. Thermal expansion coefficients slightly increase with rising temperature and concentration. The measured values of density, viscosity and refractive index were correlated as a function of temperature by using the least squares method. The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data. 相似文献
5.
An Experimental Study on Thermal Characteristics of Laurie Acid as a Latent Heat Storage Material during Melting Process
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Ahmet SARI 《中国化学工程学报》2003,(2)
The objective of this study was to establish the thermal characteristics of the lauric acid (95% purity) as a latent heat storage material filled in the annulus of vertical concentric double pipe during its melting process. The temperature data were used to determine the thermal characteristics, including the temporal temperature variations and the effects of the mass flow rate and the inlet temperature of the heat transfer fluid on the heat transfer coefficient and the heat charging fraction during the melting process. The results indicated that the time to reach to heat charging fraction of 1.0 could be altered by changing the mass flow rate and the inlet temperature of the heat transfer fluid. 相似文献
6.
Ahmet SARI 《中国化学工程学报》2003,11(2):240-243
The objective of this study was to establish the thermal characteristics of the lauric acid (95% purity) as a latent heat storage material filled in the annulus of vertical concentric double pipe during its melting process,The temperature data were used to determine the thermal characteristics,including the temporal temperature variations and the effects of the mass flow rate and the inlet temperature of the heat transfer fluid on the heat transfer coefficient and the heat charging fraction during the melting process,The results indicated that the time to reach to heat charging fraction of 1.0 could be altered by changing the mass flow rate and the inlet temperature of the heat transfer fluid. 相似文献
7.
《中国耐火材料》2012,(2)
Effects of magnesia fines addition ( 4% ,6% and 8% in mass) and spinel with different compositions ( alumina-rich,magnesia-rich and stoichiometric spinel) on thermal expansion behavior of alumina magnesia castables were researched using tabular corundum, magnesia fines,spinel fines,ρ-Al2O3,Secar-71 cement and SiO2 fume as main starting materials. The results show that: ( 1) thermal expansion coefficients of specimens with 4 mass% and 6 mass% magnesia fines have the similar change tendency,increasing slightly with temperature rising; when magnesia addition is 8 mass% ,the thermal expansion coefficient increases obviously at 1 050 ℃ and reaches the peak at 1 350 ℃ ; ( 2) when MgO content is the same,the specimen with magnesia-rich spinel has the lowest thermal expansion coefficient; ( 3) for the castables specimens with the same MgO content,the specimen with magnesia has higher thermal expansion coefficient than that with presynthesized spinel,which is related with the secondary spinelization during the heating process. 相似文献
8.
ZHEN Qiang YAN Kai ZHANG Dahai LI Wenchao 《中国耐火材料》2006,15(4):14-19
By using micron α-SisN4, SiO2, Al2O3 and h-BN as starting materials, O' -SiAION-BN ( Si2-z AlzO1 +z N2-z, z= 0. 3) composite was synthesized by reaction sintering. According to theoretical proportion ratio: n( SiO2)/n( α-Si3N4) = 1, the effects of two sintering aid composites, Y2O3 + B2O3 and Y2O3 + TiO2 at 1700℃ for 2h, were studied. The results indicate that Y2 O3 + TiO2 as sintering aid can accelerate reaction sintering of O' -SiAION-BN more effectively than Y2O3 + B2O3, and the relative density of the composites declined with the increase of BN addition (10%, 20% and 30% respectively); XRD analysis found that excessive β-Si3N4 existed in the O' -SiAION-BN composite. Therefore, in order to get more pure O' -SiAION and BN phases in the composites ore SiO2 is needed. When Y2O3 + TiO2 was used as sintering aid and addition of BN was 10%, the result of cross experiment on condition of A- n(SiO2)/n(α-Si3N4) was 1.05, 1.1 and 1.2; B-- addition of sintering aid was 2%, 4% and 6% ; C-- firing temperature was 1600℃, 1650℃ and 1700℃ ; D--soaking time was 1h, 2h and 3h, shows that the sintering properties were influenced by factors of firing temperature, soaking time, addition of sintering aid and n( SiO2 )/n(α-SisN4) in order of importance. In addition, the technical parameter A s B 3 C s D3 can achieve the highest relative density. Besides, using Pattern Recognition method, the optimized parameter range to form pure O' -SiAION and BN without β-Si3N4 remained was determined as Y 〉 1024X^2 - 230. 400X + 11.088 ( X = 0. 9999A -0. 0006C - 0. 0163D, Y = 0. 0163A + 0. 009B -0. 0014C +0. 9999D). 相似文献
9.
The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol~(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature. 相似文献
10.
Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane(TEOS) and aluminum nitrate(ANN) as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure(morphology) of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows:the molar ratio of water and ethanol to TEOS are 0:1 and 12:1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m2·g·1.The compressive strength of the geopolymer and the calcium exchange capacity(by CaCO3) of NaA zeolite prepared with the powders reached to 29 MPa and 366 mg·g·1 respectively. 相似文献
11.
利用SME和XRD等技术,系统研究了Cr2O3对SiO2-Al2O3-MgO-B2O3系玻璃和玻璃陶瓷中的作用。当Cr2O3%<1时,随着Cr2O3。含量的增加,玻璃试样的颜色由浅绿色逐渐转变成灰色;Cr2O3%>1时,镁铬(铝)类晶石,Mg(Al1.5Cr0.5)O4,在玻璃试样中析出;在玻璃陶瓷中,Cr2O3%的含量的增加有助于Mg(Al1.5Cr0.5)O4相的析出,对云母晶体的析出有抑制作用。同时还发现Cr2O3的含量对云母晶体显微组织也有显著的影响作用。 相似文献
12.
研究了La_2O_3-V_2O_5及La_2O_3-MOO_3两个催化体系对丙烷氧化脱氢反应的活性以及反应体系中加入CO_2对C_3H_6选择性及其产率的影响;并对这二个催化体系进行了比较。 相似文献
13.
Sm2O3和Gd2O3+Nd2O3改性的钛酸铅陶瓷的研制 总被引:1,自引:0,他引:1
研究了用氧化钐和氧化钕加氧化钆改性的钛酸铅压电陶瓷的机电性能。实验表明,Sm和(Gd+Nd)取代Pb时,在6—14mol%的范围内,改性钛酸铅陶瓷的钙钛矿结构是稳定的;居里温度随取代量的增加而线性下降。当钐含量为10mol%时,这种材料具有很大的机电耦合各向异性,其K_t/K_p值可大于50。这种材料,在高领阵列换能器方面,有重要的应用价值。 相似文献
14.
Bi_2O_3-B_2O_3-WO_3系统微晶玻璃的制备 总被引:1,自引:0,他引:1
采用熔融法制备了0.97[x Bi2O3(1-x)B2O3]·0.03WO3(0.25≤x≤O.75)基础玻璃,通过差热分析确定玻璃的特征温度,经热处理制备微晶玻璃.结果表明所制备的玻璃中只有x =0.67和x=0.60两个组成经热处理生成了微晶玻璃,颜色为乳黄色,晶相分别为BiO2和Bi2WO6,在扫描电镜下观察两种晶体的形貌均为颗粒状,晶粒尺寸在0.8~1.0μm.该体系玻璃的密度较大而硬度较小,但热处理后的微晶玻璃的密度和硬度均大于处理前的基础玻璃. 相似文献
15.
溶胶—凝胶法制备Fe2O3—Mn2O3—SiO2膜 总被引:1,自引:0,他引:1
用溶胶-凝胶法在浮法玻璃上制备了Fe2O3-Mn2O3-SiO2膜。对膜层的形成特性进行了观察。得出了制备良好膜层的工艺参数。对薄膜的微观结构和光谱特性进行了测定。讨论了薄膜中铁与锰的价态和配位状态。 相似文献
16.
对玻璃液相分离现象的研究是十分有意义的。过去在一些简单系统中已开展了大量深入研究。相比之下,对复杂多元系统的研究还很不够。CaO-MgO-Al_2O_2-SiO_2-P_2O_5-F系统是一个无碱多元系统,它具有显著的二液分离倾向。本工作根据TEM和DTA的实验结果,讨论了P_2O_5和B_2O_3两组分对该系统分相行为的影响,为了解多元系统中玻璃的分相规律提供了新的实验结果。 相似文献
17.
18.
助剂对铁系CO变换催化剂结构和稳定性影响的X-射线衍射研究 总被引:2,自引:0,他引:2
采用X-射线衍射法(XRD) 测定加入助剂Cr2O3、Bi2O3、CeO2 的γ-Fe2O3 催化剂还原前后的物相及氧化铁晶胞参数和晶粒度, 结果表明, Cr2O3、Bi2O3、CeO2 都没有取代Fe2O3 晶胞中的铁原子, 但它们在催化剂中的作用是不同的。Cr2O3 和Bi2O3 进入Fe2O3 的晶格中, 能抑制氧化铁晶粒的长大, 提高了催化剂的活性和稳定性; 而CeO2 则堆积在氧化铁表面, 它对氧化铁晶粒的长大作用不大, 它使催化剂活性大大提高必定有其它因素起作用。 相似文献
19.
微孔玻璃是基于分相原理得到的。人们发现,由于Na_2O-B_2O_3-SiO_2系统中同时存在两种形成玻璃网络的氧化物B_2O_3及SiO_2,电价不平衡的[BO_4]四面体趋于获得Na_2O中的游离氧而形成含富Na_2O-Ba_2O_3的相,从而与含富XiO_2相分开,当这种分相玻璃浸于稀盐 相似文献
20.
利用Al2O3-Cr2O3固溶体易形成直接结合和ZrO2的相变增韧效应,研究了Al2O3-Cr2O3-ZrO2-SiO2系高级耐火材料,结果表明:在刚玉材料中.直接结合和增韧效应能改善材料的性能。 相似文献