注浆成型《插芯注浆》法

注浆成型中,对于厚壁制品.尤其是实心的厚制品.通常采用的双面吸浆、单面吸浆,难于保证制品的成型成活率,即使制成的坯体也易出现开裂、分层等弊端.为解决厚制品注浆成型缺陷.仅介绍《插芯注浆法》.一、注浆成型基本原理注浆成型法,即把有良好流动性、厚化性能的料浆,注入到模型中,由模型吸收料浆中的水份,使模型中的料浆逐步失去水份而硬     

新骨灰瓷注浆性能实验

对新骨灰瓷注浆料采用不同于可塑泥料配方和在电解质的选择上进行了实验,成功地解决了实心注浆产品开裂、变形和针孔缺陷,空心注浆产品的泥缕缺陷。     

浅谈解决工业陶瓷泵机产品变形问题的技术措施

工业陶瓷泵机产品主要有陶瓷离心泵、陶瓷水环真空系、陶瓷喷射器、陶瓷阀门等。该产品具有耐腐蚀，耐磨损的优点，因此在化工生产中一直占有重要的位置。近年来，在湿法冶金工业中也颇受欢迎。但是，由于工业陶瓷系机产品结构严密，形状复杂，而且对机械强度又有较高的要求，因此目前国内大多采用实心注浆这一成型工艺。在生产过程中产生变形是诸多缺陷中的首要问题，成为影响经济效益的一个制约因素。产品变形的原因，一方面由于坯体本身干燥收缩不均匀产生应力，当应力超过了呈塑性状态的屈服值时引起变形；另一方面在生产过强中由于坯体…     

红陶器生产常见缺陷分析及解决方法

讨论了注浆成型红陶器坯体表面缺陷的产生原因，提出了克服缺陷的常用方法。     

读者信箱

<正>问:陶瓷墙地砖坯体缺陷产生的原因有哪些?其解决措施是什么?答:陶瓷墙地砖坯体的缺陷主要有:开裂、变形、尺寸偏差、黑心与鼓泡、斑点与溶洞等。1开裂坯体开裂主要有层裂、边裂、开口裂、风裂和后期龟裂。1.1产生原因1)配方中引入过多的颗粒游离石英,在升温和冷却过程中会产生晶型转换,引起预热裂和惊裂。2)原料中结晶水含量高水分解温度集中。     

陶瓷器注浆坯体的性质与基本参数的关系

一、序言在注浆成型中,当坯体在石膏模内达到所要厚度之后並不立即脱模,还要在模内存放一定时间以减少坯体的水分。前者叫吃浆过程,后者叫脱模过程。在空心注浆时,从排浆到脱模称之为脱模过程。在实心注浆时,从吃浆完了到脱模这个阶段称之为脱模过程。脱模过程多数情况下相当于吃浆时间的一半左右。在这个过程中,坯体由于在模内发生收缩,很容易脱模,还由于陆续脱水,使之在保持所要形状下具有一定的强度。因而脱模过程对脱     

读者信箱

问:卫生陶瓷坯体干燥有何特点?对环境温度、湿度有何要求?生产中随季节变化如何调节成形室内温度、湿度?答:卫生陶瓷利用石膏模具和泥浆注浆成形生产,同其他陶瓷制品一样采用一定比例的粘土,坯体有一定的可塑性,所以坯体干燥中也易出现开裂缺陷,这是陶瓷制品干燥的普遍性问题。     

坯体干燥时产生的缺陷分析

本文根据陶瓷坯体干燥机理，从坯体在干燥过程中河能出现的缺陷，进行了分析和论述，说明了坯体内主要是由于干燥收缩不均匀生产了应力作用，造成坯体变形和开裂。     

读者信箱

问：目前卫生陶瓷成形仍以注浆成形为主，但在冬季里注浆成形过程中往往会出现泥浆流动性差，成坯缓慢或坯体脱模困难等现象。应如何解决与克服？     

Mo-(Fe-B)-Fe混合粉末流延成型薄层坯体的干燥机理分析

流延成型Mo-(Fe-B)-Fe混合粉末流延成型薄层坯体的干燥过程非常重要，本文根据现有理论对流延坯体干燥过程的各个阶段，特别是坯体孔隙中充满液相的恒速干燥阶段（CRP）进行了分析。在恒速干燥阶段，产生了坯体的最大收缩和最大干燥应力，对引起干燥收缩的力和液相传输机制进行了分析。通过分析液相流动和固体网络之间的相互作用。可以计算孔隙液相中的压力分布。在靠近坯体干燥表面处，液相压力具有最大值，导致坯体在该处承受较大的压应力，并由此产生了不同大小的坯体收缩，从而引起干燥过程中的开裂现象，坯体开裂的可能性主要与坯体厚度和干燥速率有关，提出了避免干燥开裂的几个技术措施。     

大型固体助推发动机装药无缸浇注技术研究

对发动机装药无缸浇注技术进行了研究.按国内的二次料斗真空花板除气装药工艺,设计了药浆流入真空系统中成形复杂结构药柱的无缸浇注技术,经过小型燃烧室旋转式无缸连续浇注工艺试验、大型发动机药柱无缸浇注工艺演示试验,验证了无缸浇注的技术可行性.提出在大型固体助推发动机装药中采用无缸浇注工艺成型途径.     

The effect of solidification on the casting window after bubble entrainment

The objective of this work is to investigate the feasibility of extending the velocity boundary during the slot die casting of a polymer film, by studying the dynamics of entrained bubbles as they transition from the fluid to the solid phase. The solution of interest is a relatively high viscosity non-Newtonian solution. A 2D computational fluid dynamics model, using ANSYS FLUENT 13.0 software, was developed to analyze this behavior. The volume of fluid method and enthalpy–porosity technique were used to track the air (i.e., entrained bubbles) and fluid phases and the solidification of the solution, respectively. It has been found that for this class of solution, bubbles that are entrained in the fluid phase will not diffuse out of the fluid due to the stresses formed during solidification. Thus, for relatively high viscosity non-Newtonian solution, the upper boundary of the casting window cannot be extended after a defect has originated in the film during the casting process.     

Dewatering of spontaneous-coagulation-cast alumina ceramic gel by filtrating with low pressure

Water removal in colloidal processing is a tough and crucial problem because deformation and cracking of the wet body easily happen during the drying process. Inspired by conventional pressure filtration (PF), we combined spontaneous coagulation casting (SCC) with PF to partially remove water from the gelled sample before drying for the purpose of lessening the risk of cracking and shortening the drying period. The effect of pressure, holding time, and solid loading on the particle packing ratio of wet samples, the drying process, and the bulk density and homogeneity of green and sintered bodies was surveyed systemically. The PF process of 0.4 MPa for 2 h was optimized based on dewatering ratio from ceramic slurries. The particle packing ratio of the pressure-filtrated samples increased with the solid loading of ceramic slurries, and 61 vol% was obtained for the slurry with 56 vol% solid loading. The drying time of the pressure-filtrated samples was shortened by as much as 42%–53% compared with that of the gelled samples, and the linear shrinkage for the pressure-filtrated samples during drying was only approximately 0.5%, much smaller than that of the gelled samples (2.4%–4.6%). Furthermore, the bulk density of the pressure-filtrated green bodies was more than 2% higher than that of the gelled green bodies, and more homogeneous green bodies were obtained by PF than by SCC. The alumina ceramic with 98.8% relative density and a homogenous density distribution was obtained after being sintered at 1550 °C for 2 h.     

Preparation and properties of lightweight,conformal, and load-bearing TiC/Si3N4 absorbing composites by gel casting

In view of the lack of conformal, load-bearing, light-weight, and high temperature-resistant integrated wave-absorbing composites suitable for extremely complex conditions, the gel-casting process was successfully applied to porous Si₃N₄ wave-absorbing composites in this work. A universal low-slurry for gel casting was prepared by using two dispersants acting together (tetramethylammonium hydroxide solution and sodium lauryl sulfate), which ensured the smooth completion of the gel casting process. Combining the thermogravimetric and differential thermal gravity curves of the composite green body, reasonable parameters of the rubber discharge process are given to avoid the problem of the green body swelling and cracking. The porous TiC/Si₃N₄ composites were successfully prepared by holding them at 1650°C for 3 h. The bending strength, density, minimum reflection loss, absorption bandwidth, and matched thickness in the P-band of the composites with 30 wt.% TiC addition were 54.08 ± 3.02 MPa, 1.906 g/cm³, -37.75 dB, 1.9 GHz, and 4.1 mm, respectively. The electromagnetic wave loss mechanisms of the composites are a combination of conductivity loss, multiple reflections and scattering, interfacial polarization, and defect polarization.     

Indirect solid freeform fabrication by binder assisted slip casting

A method has been developed for the consolidation of ceramic bodies in molds prepared by solid freeform fabrication. The method is based on slip casting with an added latex binder. The latex binder makes it possible to create internal structures, such as pore channels, without the cracking that usually takes place when shrinkage is obstructed by internal mold structures. The latex binder adds plasticity to the consolidating body in the wet state. This was observed by rheological measurements during slip casting. Measurements of mechanical properties showed that the latex binder also adds plasticity and strength in the dry state.     

硫磺砂浆模具的制作

模具在陶瓷工业生产中起着非常重要的作用,传统方法一般用硫磺制作母模与胎模,但制作过程中对操作较为苛刻,为改善硫磺模具制作过程的可操作性,研究通过在硫磺模具中引入硫磺砂浆的概念,采用一次熔制两次浇注一次成型的工艺,简化了硫磺模具的制作程序,提高了强度,减小了制作过程中的收缩开裂和变形。详细阐述了改性硫磺模具的制作方法及制...     

Studies of drying and sintering characteristics of gelcast BaTiO3-based ceramic parts

Drying green gelcast parts is an essential step in the gelcasting manufacturing process. In this work, the liquid desiccant method was used for drying of BaTiO₃-based semiconducting ceramic gelcast parts. The results show that the loading level of ceramic powders and the liquid desiccant concentration significantly effect the drying process and the sintering characteristics of the ceramic parts. Lowering the loading level of ceramic powders and increasing the concentration of the liquid desiccant, non-uniform and differential drying in various regions due to great solvent gradient, induces structural and residual stresses which cause defects, such as cracking, bending and other malformations, which make the articles useless during the drying process and sintering procedure. However, when the solid loading of green gelcast parts is increased to more than 45 vol.%, the stresses developed during drying can be greatly reduced, and a higher concentration of the liquid desiccant can be used without inducing defects in the drying process and defect free ceramic with a smooth surface can be obtained. Moreover, the effects of loading level of ceramic powders and thickness of parts on the density of ceramic parts were studied. Higher solid content in the gel, and lower thickness of parts, increase the density of ceramics.     

铝合金结构件液固复合挤压模具的设计

挤压铸造和固态挤压的有效结合，能够得到组织致密的结构件。通过增加补偿板和垫板，能够较方便的实现挤压铸造后的固态挤压工序。本文介绍了针对圆柱形制件的液固复合挤压模具的模具结构和工作过程，这种一模两工序的设计思想也可应用于其他结构件的成形。     

减少轮胎模具中铝合金铸件缺陷的试验研究

针对铝合金铸件存在的缺陷，重点研究了铝合金的精炼净化工艺，提高汽车轮胎模具的外观质量。考察了FDU除气装置进行吹氩处理工艺的铝合金精炼效果及铝合金中气孔和夹杂物去除的效果。现场实践证明，采用FDU除气装置进行吹氩处理的精炼工艺，使铸件质量得到明显提高。