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水玻璃作为型砂粘结剂已有近百年历史.目前水玻璃硬化剂大致可分为三大类:气体(C02),粉末(炉渣、硅铁粉等)和液体(有机酯,碳酸酯等)。水玻璃炉渣自硬砂在我国的造纸机械和机床铸件生声中应用已有近二十年的历史了。 相似文献
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李显文 《特种铸造及有色合金》1995,(4):33-34
三通铸件精铸工艺改进宝鸡石油机械厂李显文我厂熔模铸造采用水玻璃粘结剂,石英砂耐火材料,NH4Cl硬化剂制壳。由于生产的品种多,数量少,现场大量采用石膏模具压制蜡模,金属模具使用在批量多、表面精度要求高的精密铸件上。我厂接到出口产品上的三通铸件任务,考... 相似文献
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本文概述铸造型砂应用一些主要粘结剂的发展过程及其化学分子结构和性能。文中提到第一次世界大战后,才广泛采用型芯油作型砂粘结剂。40年代中期开始应用人造脲醛树脂和酚醛树脂作型砂粘结剂。到50年代初期,在欧州发展起来的油一氧自硬砂,使型芯能在芯盒中自硬;同时,出现了水玻璃CO_2砂,到50年代末期,出现了酸固化的呋喃树脂粘结剂,使单件小批量生产车间制芯工艺发生了革命性变化。60年代出现了醇酸异氰酸盐,同时,也出现了无机硬化剂和有机硬化剂的水玻璃自硬砂。70年代开始,发展出酚基尿烷系快速硬化粘结剂,使生产效率大大提高。70年代中期,又重新研究酸固化的酚基树脂,称为新的酚基树脂;同时,也研究出无机磷酸盐和波兰发展出SYNCORE法,近几年来,欧、美又出现SO_2硬化法(即Sapic法)。最后,列举美、英、德三国每年消耗有机粘结剂的吨位数字,我国目前与之相比,还有很大差距,为了节约能源,为了提高铸件质量和劳动生产率,必须从烘模砂中解放出来走向化学自硬砂的道路。型砂粘结剂对铸件的质量和产量有直接的影响。铸件的气孔、粘砂、结疤、热裂和表面质量等,都与所使用的粘结剂有很大关系。研究和改进型砂粘结剂,已成为提高铸件质量和增加产量的重要途径。型砂粘结剂又区分为有机和无机二大系统,一般讲,无机粘结剂多用于制造铸型和简单形状的型芯;有机粘结剂多用于制造复杂形状的型芯,两者之间的主要区别是:无机粘结剂是热稳定性的,受热时状态上没有多少变化或者没有变化;反之,有机粘结剂不管它的成分怎样,浇注时受热分解,产生气体排出遗留碳质在砂粒周围,而且浇注以后,有机粘结剂的溃散速度,完全取决于它的化学成分。在以往三十多年中,由于人类努力创造,出现了许许多多的新型化学粘结剂,使铸造工业面貌发生了根本性的变化,型砂粘结剂之所以得到迅速发展,在许多情况下都是由于为了其他工业研究出来的新粘结剂,然后,将这些粘结剂应用于金属铸件。 相似文献
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摆杆铸件的熔模精密铸造工艺实践 总被引:1,自引:1,他引:0
采用石蜡-硬脂酸低温模料制造熔模(蜡模),用水玻璃粘结剂制造型壳,精密铸造生产剪羊毛机摆杆铸件,试验研究熔模制造工艺、水玻璃型壳工艺和焙烧工艺的技术参数,为生产合格型壳和精密铸件提供技术保障. 相似文献
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目前,铸造界在造型中为节约资源、降低公害,大多数已使用以呋喃树脂为主的有机系粘结剂。但是,在铸钢和球铁生产中使用这类有机粘结剂,容易引起增碳和球化不良等问题。此外,砂温对铸型的硬化情况影响很大,而砂温的控制又很复杂,因此至今在铸钢、不锈钢铸件以及一般中小铸件的铸造厂中依然使用着硅酸钠(即水玻璃)等无机系粘结剂。但是,过去采用这种CO_2造型法,型砂中须加入5~6%水玻璃,粘结剂用量要比有机系粘结剂用得多,而且型砂的溃散性也较差。日本铸造技术普及协会等研制的VRH(真空置换硬化)法,是把加有2~3%水玻璃的混合砂放在气密室内密闭,用真空泵抽空减压后再充入CO_2 相似文献
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叙述了铸造工业对合成粘结剂应保证铸件质量和符合环保趋势的两个基本要求的内容;介绍了工业发达国家在芯砂粘结剂和自硬砂粘结剂方面的改进工作情况及其所取得的技术进展;指出了在水溶性粘结剂方面目前的研究工作只是起步,水玻璃的粘结能力远未被充分利用等问题。 相似文献
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应用硅溶胶粘结剂配制表面层涂料,水玻璃粘结剂配制加固层涂料,所制复合型壳经生产验证表明,有效地提高了熔模铸件的表面质量。经材料、工时、动力消耗和质量等项核算,复合型壳与单一水玻璃型壳的制壳成本相当。 相似文献
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在过去的二十多年里,化学粘结剂型砂在型芯制造中占绝对优势。虽然有机粘结剂的使用特别好,但是在混砂、硬化和存放时会发散出臭气和有毒的蒸汽,浇注和落砂时会产生烟气和分解产物以及成本较高。这就使得人们有兴趣去发展无机粘结剂。最常用的无机粘结剂是以水玻璃和磷酸盐为基的水基材料。它们在混砂、浇注和落砂操作时不会产生苯酚、甲醛等有机蒸汽,但是其缺点是强度较低以及落砂和再生问题,已经阻碍了无机粘结剂的广泛使用。水玻璃粘结剂在1898年作为英国专利。1950年以前还没有在铸造厂广泛的应用。1960年初,研究了许多不用二氧化碳气体来硬化水 相似文献
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中国的精密铸造有两种工艺。第一种是采取水玻璃为粘结剂的熔模铸造工艺,该方法主要用于生产碳钢、低合金钢、球铁等铸件,面向于汽车工业、工程机械、铁路及轨道交通、泵阀等领域。大部分铸件为国内市场 相似文献
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Xia Zhou Jinzong Yang Depeng Su Guohui Qu 《Journal of Materials Processing Technology》2009,209(14):5394-5398
A new binder composed of α-starch, kaolin, sodium silicate, dextrin, phosphate and water in proportions 2.5–4.0%, 1.5–3.0%, 0.55%, 0.35%, 0.04% and 2.5–3.5% by weight percent respectively has been developed. The high-temperature resistant mechanism of the mold and core sand bonded with α-starch composite binder was studied by way of differential scanning calorimetry (DSC), X-ray diffraction (XRD), infrared (IR) spectra and scanning electron microscopy (SEM) analyses without sand or on a sand base. It is believed that the high-temperature strength of the sand mold or sand core is mainly dependent on the cohesive strength of the adhesive membrane between sand grains. When the binder was heated over 600 °C, the kaolin in it reacted with the sodium silicate and phosphate separately, forming Al–O–Si three-dimensional skeleton and heat-resistant AlPO4, thus, the binder is provided with higher high-temperature resistant strength. This conclusion is also confirmed by the experimental research on the high-temperature mechanical properties of the binder bonded sand and the microstructure observation of the binding film. The research on the high-temperature resistant mechanism of the starch binder bonded sand is helpful to its high-temperature performance optimization and its application in the foundry industry. 相似文献
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《中国铸造》2016,(6):427-432
The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with “dry” or “wet” activation of inorganic binder in waste moulding sand mixtures physicaly hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the folowing cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermaly loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermaly treated inorganic binder, each of the examined processes employed the surface phenomenon usualy associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclicaly prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands alows them to be reused for manufacture of next moulds. Thus, the two proposed methods for cyclicaly processing used moulding sands containing sodium silicate, subject to microwave hardening, are suitable for economic and ecological circulation moulding mixtures. 相似文献
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典型方法和材料对水玻璃的改性效果与机制 总被引:1,自引:0,他引:1
研究比较了超声处理、纳米粉末改性、复合材料改性等水玻璃粘结剂改性方法及材料对水玻璃粘结剂的改性效果;分析了水玻璃的改性机制。试验结果表明,超声处理虽然提高了水玻璃砂的常温强度,却也恶化了溃散性;水玻璃经过纳米氧化物粉末改性后,适量纳米氧化物粉末可以在一定程度上改善水玻璃砂的溃散性,但常温强度却不能得到较大幅度的提高,作者开发的复合改性剂,既可提高水玻璃砂的常温强度,又可改善水玻璃砂的溃散性。借助XPS和SEM微观分析的方法,探讨了水玻璃粘结剂改性方法及材料对水玻璃粘结剂的改性机理。 相似文献
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This paper presents a new method of modifying sodium silicate binder with ultra-fine powders. The sodium silicate binder modified by ultra-fine powder A and the organic B can reduce the addition amount of the binder. The results indicate that the 24 h strength has increased by 39.9% at room temperature and the residual strength has decreased by 30.7% at 800℃, compared to the conventional sodium silicate. An available material to improve the moisture resistance was also found by adding about 2% more inorganic C, and it can increase the moist strength by 20%. In the end, the microanalyses are given to explain the modifying machanism, i. e., the ultra-fine powder A can refine the sodium silicate binder to avoid holes in the binder bond, which can increase the 24 h strength at room temperture, and can lead to more cracks in the bond after the molding sand is heated to 800℃. This is because of the stress caused by the new eutectic complex of modified sodium silicate binder. 相似文献
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对比研究了普通一次微波硬化、有机酯硬化、有机酯-微波复合硬化三种水玻璃砂硬化工艺的性能.结果表明,与普通一次微波加热硬化相比,有机酯-微波加热复合硬化工艺可使砂型在微波加热阶段不带模具加热,当有机酯的加入量为水玻璃质量的1.5%时,恒湿瓶中4h存放强度较普通一次微波加热硬化提高了70%;较之于有机酯硬化工艺,有机酯-微波加热复合硬化工艺的水玻璃加入量少、硬化速度快、硬化强度高.进一步系统研究了其他工艺参数(微波加热功率和时间)对有机酯-微波加热复合硬化水玻璃砂型存放强度的影响,并通过扫描电镜观察分析了该工艺下的砂样粘结桥微观结构和硬化机理. 相似文献