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1.
碳化硅陶瓷的热等静压烧结   总被引:11,自引:3,他引:11  
系统地研究了不同添加剂(如Al2O3,AlN和B4C等)在热等静压(HIP)烧结条件下对SiC陶瓷之致密机理,显微结构以及力学性能的影响,结果表明:在HIP烧结过程中,Al2O3可以与SiC颗粒表面的SiO2生成低共熔的铝硅酸盐玻璃相,并有效地促进SiC陶瓷的致密化,当添加3%(以质量计)Al2O3时,采用HIP烧结工艺,在1850℃温度和200MPa压力下降结1h,就可获得相对密度和抗弯强度分别  相似文献   

2.
苯基三甲氧基硅烷制备工艺   总被引:4,自引:0,他引:4  
由苯基三氯硅烷(PhSiCl3)和甲醇(CH3OH)醇解制备苯基三甲氧基硅烷[P hSi(OCH3)3]过程中,采取及时驱除氯化氢(HCl)的方法,控制副反应发生 ,可提高PhSi(OCH3)3的质量,收率达80%以上。  相似文献   

3.
苯基三甲氧基硅烷制备工艺   总被引:1,自引:0,他引:1  
由苯基三氯硅烷(PhSiCl_3)和甲醇(CH_3OH)醇解制备苯基三甲氧基硅烷[PhSi(OCH_3)_3〕过程中,采取及时驱除氯化氢(HCl)的方法,控制副反应发生,可提高PhSi(OCH_3)_3的质量,收率达80%以上。  相似文献   

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Al_2(OH)_5Cl的制造含铝原料用盐酸在20~95℃下处理,控制一定条件可得到Al_2(OH)_5Cl沉淀。用偏高岭土(Al_2O_3、2SiO_2、2H_2O)煅烧后的硅酸铝时作原料时,其生产成本较低。(郦东浩)Al_2(OH)_5Cl的制造@郦东浩...  相似文献   

5.
程强 《耐火与石灰》1996,21(6):58-63
本文研究了抗氧化剂Al8B4C7和Al4SiC4添加到含碳耐火材料中的性状和效果,讨论了其抗氧化的机量。Al8B4C7及Al4SiC4的抗水化性能良好,故可实际应用,Al8B4C7和Al24SiC4在耐火材料表面和CO(气)反应,分别生成Al2O3-B2O3和A2O3-SiO2保护层,抑制了耐火材料的氧化。  相似文献   

6.
SiC—Al2O3基复相陶瓷的N2—HIP研究   总被引:3,自引:0,他引:3  
通过对热压SiC-Al2O3复合材料进行了N2-HIP后处理,制备得到Si3N4-AlN=SiC-Al2O3梯度材料,经N2-HIP处理后,材料抗弯强度提高35%-95%,并得到经强度达1030MPa的SieN4-AlN/SiCp-SiCW-Al2O3复合材料。  相似文献   

7.
溶胶—凝胶法莫来石被覆SiC复合微粒子的制备   总被引:3,自引:1,他引:2  
本文采用溶胶-凝胶法以组成为3Al2O3.2SiO2的混合溶胶分别于和压力条件下,对SiC微细粉进行包覆处理,该涂覆层在低于1000℃下经1h热处理可结晶成莫来石层,研究了涂覆溶胶浓度、涂覆压力对涂层厚度、结晶化温度等的影响,涂覆后的SiC微粉在中高温的表面抗氧化性明显提高。  相似文献   

8.
Al4SiC4是一种极好的抗水化化合物,它作为含炭耐火材料的抗氧化剂,对其性能用作用进行了研究,并探讨了相应机理。Al4SiC4添加到含炭耐火材料中,起初与CO反应,生成Al2O3、SiC和Co反应后,如果温度在-1560℃以下,生成的SiC和Al2Oe将进一步与CO应生成莫来石(Al6SiC2O13)和Co。在耐火材料表面进行的上述反应形成了保护层,这就阻止了耐火材料的氧化。为此,Al4SiC4  相似文献   

9.
新型复相陶瓷刀具材料Jx-2-I协同增韧补强机理的研究   总被引:1,自引:0,他引:1  
本文研制成功的新型陶瓷刀具材料—SiC晶须(SiCw)增韧和SiC颗粒弥散增韧Al2O3陶瓷刀具Jx-2-I,该刀具材料具有高的抗弯强度和断裂韧性等优点;对比A(Al2O3)、AP(Al2O3/SiCp)、AW(Al2O3/SiCw)、Jx-1(Al2O3/SiCw)和Jx-2-1(Al2O3/SiCp/SiCw)等陶瓷材料的力学性能可以看出,在Jx-2-I材料中具有明显的增韧补强叠加效应;本文在热失配分析和微观结构观察的基础上详细研究了Jx-2-I刀具材料的增韧补强机理,系统研究了Jx-2-I中各种增韧补强机理之间的协同效应。  相似文献   

10.
CaO-Al_2O_3-SiO_2玻璃表面上晶体生长动力学和分相影响杨晓晶,李家治(中国科学院上海硅酸盐研究所200050)许淑惠(西北轻工业学院712081)SurfaceCrystalGrowthKineticsinCaO-Al_2O_3-SiO...  相似文献   

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Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.  相似文献   

13.
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.  相似文献   

14.
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.  相似文献   

15.
A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by 1H MAS NMR. For direct comparison purposes, an SiO2 coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N2 absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.  相似文献   

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Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.  相似文献   

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