精密铸造硅溶胶模壳的制造工艺

介绍用石蜡-硬脂酸低温模料，生产铸件的熔模和用精密铸造硅溶胶，作为制壳粘结刑，制造铸件的模壳的工艺要求。主要研究熔模制造工艺、硅溶胶模壳工艺和焙烧工艺。五年多来的生产实践充分证明精密铸造硅溶胶模壳制造工艺是成熟的。为生产合格模壳和精密铸件提供了技术保障。     

对熔模铸造现行制壳工艺的改进和讨论

中温模料硅溶胶制壳工艺是目前国内外用于精密铸件生产的主流工艺。然而此工艺的制壳生产周期长,而且存在因面层型壳缺陷导致铸件缺陷的问题。采用了面层浆料加入防裂剂、面层大风力干燥、面层采用大粒径硅溶胶、取消涂二层前预湿、取消涂面层前沾硅溶胶的工艺举措。结果表明,面层型壳的强度得到了提高,面层型壳的缺陷减少,涂层干燥时间缩短,铸件一次性合格率增大。     

一种高性能熔模铸造复合型壳的制备工艺

为实现近净形熔模铸造,介绍了一种高性能熔模铸造复合型壳的制备工艺,其中第1~3层使用硅酸乙酯涂料,背层使用硅溶胶涂料。此工艺避免了硅酸乙酯-硅溶胶交替硬化复合型壳工艺由于硅酸乙酯涂料与硅溶胶涂料相互污染,而使涂料使用寿命缩短的情况,提高了涂料的利用率,有利于生产成本的降低,所得铸件精度可以达到CT5级,表面粗糙度可以达到Ra0.8~1.6μm。     

硅溶胶-硅酸乙酯交替复合制壳工艺在不锈钢精铸生产中的应用

介绍了硅溶胶—硅酸乙酯涂料的配制过程及硅溶胶—硅酸乙酯的交替复合制壳工艺，采用硅溶胶—硅酸乙酯复合型壳对新材料CF—8M不锈钢精密铸件进行了生产应用。结果表明，采用硅溶胶—硅酸乙酯交替复合制壳工艺，型壳质量有很大提高，生产的不锈钢精铸件表面质量和尺寸精度都得到很大提高。     

低温蜡-硅溶胶型壳的应用实践

分析了水玻璃型壳、复合型壳、中温蜡-硅溶胶型壳和低温蜡-硅溶胶型壳4种制壳工艺的优缺点,指出低温蜡-硅溶胶型壳工艺适用于质量要求一般的铸件,中温蜡-硅溶胶型壳工艺适用于高质量要求的小件、特小件。介绍了低温蜡-硅溶胶型壳的生产工艺要点。     

熔模铸造型壳制造与增强快干硅溶胶

熔模铸造是生产精密铸件的一种先进工艺，硅溶胶是影响型壳质量的重要因素。增强快干硅溶胶有利于缩短制壳周期，提高制壳效率。同时提高型壳的常温强度，对避免型壳开裂有积极作用。     

硅溶胶制壳工艺探讨

探讨硅溶胶型壳制壳工艺中几个主要问题，以求提高工艺技术水平和铸件质量。     

简易有效的深长孔铸造

简易有效的深长孔铸造白银柯登精密铸造阀门有限公司申宝云硅溶胶制壳工艺存在自然干燥周期长，遇到曲线或孔洞类的复杂铸件易出现干燥不良及清理困难的不利因素。尤其是铸件中的直径较小，相对较深和较长的盲孔，在制壳时，由于背层型壳在不断挂砂加厚过程中，端部的孔径...     

熔模铸造硅溶胶模壳制造工艺

介绍用石蜡-硬脂酸低温模料制作熔模,用硅溶胶作粘结剂制造模壳的工艺。包括熔模制造工艺、硅溶胶模壳工艺和焙烧工艺。生产实践证明,铸造硅溶胶模壳制造工艺是成熟的,为生产合格模壳和精密铸件提供了技术保障。     

一种医用钛合金铸件熔模铸造工艺设计

一种医用钛合金铸件采用ZTC4钛合金,由熔模铸造工艺生产.通过对浇注系统进行模拟分析,确定适用于生产该医用钛合金铸件的浇注系统.面层采用1#粘结剂制壳工艺、加固层硅溶胶制壳工艺,采用蒸汽脱蜡及合适的焙烧工艺、离心浇注工艺获得医用钛合金铸件,铸件经过修整、热等静压等工序获得了内部及外观质量好、尺寸精度高的钛合金铸件,批量...     

Characterization of the chemical conversion films that form on Mg−Al alloy in colloidal silica solution

Chemical conversion treatment of Mg−Al alloy (AZ91) using colloidal silica as an alternative to chromate conversion was investigated as a function of solution pH, temperature, solution conditions, and treatment time. The solution used for the colloidal silica coating consisted of colloidal silica, titanium sulfate, and cobalt ions to maintain good anti-corrosion and adhesion properties. Adding CoSO₄ to the colloidal silica solution enhanced the adhesion force between the silica film and magnesium substrate. The optimum conditions for the chemical conversion treatment solution were pH 2, 90-sec treatment, and 25°C.     

熔模铸造用硅溶胶粘结剂综述

介绍了熔模铸造用硅溶胶应用与研究情况，尤其是快干硅溶胶研究的进展和硅溶胶理论研究进展，包括硅溶胶稳定性和硅溶胶粒粒径与强度的关系，预测了硅溶胶发展方向。     

硅溶胶的凝胶化包覆对氧化铝烧结性能的影响

在探讨影响硅溶胶凝胶化因素的基础上,通过控制硅溶胶的凝胶化条件使其包覆在氧化铝粉体表面,进而研究了不同硅溶胶添加量对氧化铝陶瓷烧结性能的影响规律。结果发现:控制体系的pH值5～7、固含量10%～15%时,硅溶胶极易发生凝胶化转变,而且随着环境温度的升高,凝胶化进程加快;当在氧化铝粉体中添加2%～10%的硅溶胶时,1650℃烧结后均可获得致密结构的陶瓷,且有大量莫来石生成,而过多硅溶胶的添加(超过15%)将不利于陶瓷体的致密烧结。     

Mechanical effect of colloidal silica in copper chemical mechanical planarization

The mechanical effect of colloidal silica concentration in copper chemical mechanical planarization (CMP) is considered in this paper by using friction force monitoring system. The copper peak was detected in the result of the energy-dispersive X-ray (EDX) spectra of the polishing residues. The addition of colloidal silica into copper CMP slurry increased both the material removal rate and the friction force. During CMP, as the concentration of the colloidal silica was increased, the temperature generated by the friction force also increased. To understand effect of abrasive concentration on the material removal and friction force, we considered the material removal and the friction energy for a single abrasive. The surface of the polished copper film was measured by X-ray photoelectron spectroscopy (XPS). All the material removal rates as a function of friction energy after polishing with various concentrations of colloidal silica had a non-linear characteristic.     

Fabrication of perforated sub-micron silica shells

A new synthetic approach for fabrication of perforated hollow silica morphologies using colloidal template assemblies is demonstrated. As proof-of-principle, the polystyrene/silver colloidal assemblies had chemically modified surfaces. The template dissolution resulted in the fabrication of the submicron perforated hollow silica shells. The morphologies are characterized by transmission electron microscopy, energy dispersive spectroscopy and plasmon light extinction spectrophotometry.     

Poly(vinyl alcohol)-colloidal silica composite membranes for fuel cells

The aim of this study is to develop an environmentally and friendly poly(vinyl alcohol) based low cost membrane with improved ionic conductivity, thermal and mechanical stability. In this work, the effect of colloidal silica content on membrane properties was investigated. Sulfosuccinic acid (SSA) was used as the sulfonating agent. In order to enhance the mechanical and ionic conduction properties, colloidal silica was used. The range of silica content in the membrane solution investigated was 5–20%. For the characterizations, the synthesized membranes were subjected to FT-IR, TGA, tensile strength analysis, water uptake, ion exchange capacity (IEC) and impedance measurements for proton conductivity. Synthesized membranes demonstrated high water uptake (up to 80%) without swelling, high ion exchange capacities was found to increase with increasing SSA content. The proton conductivity of CS doped membranes increased with increase in temperature and the temperature dependence showed significant change in the CS doped membranes. An increase in the values of the proton conductivity was driven by the mobility of free charges (free ions) as the temperature was increased. Addition of SSA and CS to the polymer matrix improved the thermal stability of the membranes. It was also discovered that membranes were in a composite structure and colloidal silica particles did not contribute to the structure of the polymer matrix at the molecular level. Mechanical durability of the membranes having SSA content above 15% decreased and these membranes showed a more fragile structure.     

Time-lapse,three-dimensional in situ imaging of ice crystal growth in a colloidal silica suspension

The freezing of colloidal suspensions is encountered in many natural and engineering processes such as the freezing of soils, food engineering and cryobiology. It can also be used as a bio-inspired, versatile and environmentally friendly processing route for porous materials and composites. Yet, it is still a puzzling phenomenon with many unexplained features, owing to the complexity of the system and the space and time scales at which the process should be investigated. This study demonstrates the interest in fast X-ray computed tomography for providing time-lapse, three-dimensional, in situ imaging of ice crystal growth in a colloidal silica suspension. The experimental measurements show that the local increase in colloid concentration does not affect the growth kinetics of the crystals until the colloidal particles become closely packed. For particles much smaller than ice crystals, the concentrated colloidal suspension is equivalent to a simple liquid phase with higher viscosity and a freezing point determined by the concentration of colloidal particles.     

聚乙烯蜡-硅溶胶熔模铸造工艺

介绍了用聚乙烯蜡低温模料制作熔模、用硅溶胶作粘结剂制造型壳的工艺.多年生产实践证明,采用聚乙烯蜡制模的硅溶胶型壳制造工艺是成熟的,可以达到减少污染、降低成本的效果.