基于机器视觉的氮化硅陶瓷轴承表面缺陷检测技术

为提高缺陷检测效率和精度,针对人工检测氮化硅陶瓷轴承球表面缺陷成本高、效率低的缺陷,分析机器视觉技术特点.通过自主搭建氮化硅陶瓷轴承球检测平台,采用CCD相机采集表面缺陷图像,分析氮化硅陶瓷轴承球表面缺陷特征;采用灰度处理、中值滤波、缺陷提取及边缘检测等操作,有效识别氮化硅陶瓷球表面缺陷.该方法对氮化硅陶瓷球表面缺陷的...     

氮化硅轴承球表面层残余应力的形成机理及试验研究

本文论述了烧结热应力及研磨加工对氮化硅轴承球表面残余应力的影响机理.通过比容积测定,对氮化硅轴承球表面残余应力分布进行了分析计算,并就研磨加工对氮化硅轴承球表面残余应力的影响进行了试验研究.     

汽车保险杠注塑CAE工艺分析

从汽车保险杠的注塑成型工艺入手,利用CAE软件对汽车保险杠模具的浇注系统进行了全面的研究分析,通过分析成型制品所需的注塑充填时间、注射不同阶段的温度、压力、产品表面熔接线及气穴分布等,并结合产品特点成功设计了八点针阀式浇注系统。通过数值模拟试验验证了8点针阀式热流道进胶系统能带来平稳的注塑填充效果、较低的注塑压力、合理的前锋温度和较好的熔接质量。     

基于遗传算法的注塑成型工艺参数优化

以某杯形塑件为例,设计了随形冷却水道模具。在Moldflow软件模拟注塑成型过程的基础上,利用正交试验法分析了熔体温度、注射压力、保压压力和保压时间等工艺参数对制品成型周期的影响。通过遗传算法和Moldflow获得的最佳注塑工艺参数为熔体温度180℃,注射压力22 MPa,保压压力16 MPa,保压时间8 s,成型周期14. 11 s。在最佳工艺参数组合下进行注塑成型试验,平均注塑成型周期为14. 19 s。结果表明,模拟结果和试验结果之间相接近。将数值模拟和遗传算法相结合,可以有效提高运算速度和优化效率。     

制样方式及注塑工艺对聚酰胺6抗冲击性能的影响

通过改变注塑压力、注塑速度、模具温度、注塑温度等注塑成型工艺参数,研究了两种制样方式对改性聚酰胺(PA)6抗冲击性能的影响.结果表明:相同注塑成型工艺条件下,自带缺口试样的冲击强度都高于自制缺口的试样;注塑压力和注塑速度对自带缺口试样的冲击强度影响较大,但对自制缺口试样的冲击强度影响不大;模具温度和注塑温度对两种制样方...     

薄壁塑件注塑成型和注塑压缩成型工艺对比分析

基于Moldflow 2018软件对薄壁塑件进行注塑成型和注塑压缩成型模拟,分别从V/P切换时的压力、填充末端压力、流动前沿温度、平均体积收缩率、气穴、熔接线和翘曲变形等方面进行对比分析。结果表明:采用注塑压缩成型工艺加工的薄壁塑件质量优于由注塑成型工艺得到的薄壁塑件,该对比分析结果对薄壁塑件的实际加工具有一定的指导意义。     

注塑成型工艺对PBT收缩率的影响

论述了注塑成型中压力、温度、时间、速度等工艺条件对聚对苯二甲酸丁二醇酯注塑制品收缩率的影响,并以此为依据拟定了最佳成型工艺条件。     

陶瓷轴承球的应用和生产加工

笔者主要介绍了氮化硅陶瓷轴承球具有的优点和特性,并介绍了其应用领域及范围。通过对氮化硅陶瓷材料性能的对比分析,确定其生产加工工艺,最终生产出高于G5级标准要求的氮化硅陶瓷球。     

氮化硅陶瓷轴承在有机硅室温胶搅拌釜上的应用

分析了有机硅室温胶装置中搅拌釜底部滑动轴承在使用中易于磨损，更换频繁的原因。论述了氮化硅陶瓷材料的特点，选择了氮化硅陶瓷轴承作为有机硅室温胶搅釜底轴承并进行了相应设计。运行结果表明，采用氮化硅陶瓷轴承作为有机硅室温胶搅拌釜等设备的底部轴承具有耐磨损，耐高温，无污染，使用寿命长等特点，且有良好的经济效益和推广使用价值。     

山东工陶院陶瓷轴承球制备技术世界领先

国家建材局山东工业陶瓷研究设计院在氮化硅陶瓷轴承球研究开发上获重大突破。他们生产的氮化硅轴承球精度等级已达目前国际最高精度级Ｇ5级 ,居世界领先水平。陶瓷轴承球是目前世界上替代传统的钢制轴承球的最先进产品 ,广泛应用于航天、军事、电子、冶金、能源等领域。 90年代以来 ,一些发达国家相继建成多条陶瓷轴承球生产线 ,我国每年须大量进口陶瓷轴承球 ,以满足各行业的需要。山东工陶院在“八五”期间完成了国家“陶瓷轴承球的研制与开发”专题项目 ,“九五”又继续承担了国家重点科技攻关“氮化硅陶瓷球及陶瓷轴承批量制备技术的开…     

Rheological and thermal debinding behaviors of silicon nitride in powder injection molding

In powder injection molding process, it is important to analyze the rheological and thermal debinding behaviors of feedstock, because they can directly affect the final quality of products. Therefore, for the silicon nitride based feedstocks, the rheological and thermal debinding behaviors were investigated and compared between feedstocks prepared with the combination of two types of powders and sintering aid ratios. At first, the optimal solids loading for each feedstock was determined based on the results of the torque rheometer experiment. The viscosity of the feedstocks was measured using the capillary rheometer, and rheological properties were evaluated with the Power Law-Arrhenius model. Silicon nitride (JPN) feedstock with 5 wt% yttria and 2 wt% alumina (JPN+5Y2A) had the highest moldability index among all feedstocks. The powders with sintering aid ratio of 5 wt% yttria and 2 wt% alumina made the feedstocks have a high moldability index. Thermogravimetric experiment was also performed to analyze the pyrolysis behavior of the feedstocks, and the apparent activation energies for each feedstock were obtained using Kissinger method with the thermogravimetric analysis results. Based on the results, the master decomposition curve (MDC) was developed, and the utility of MDC for optimizing the thermal debinding process was verified.     

高强度低介电氮化硅陶瓷的制备及性能研究

采用氮化硅（Si3N4）、氮化硼（BN）等原料,通过气氛压力烧结工艺（GPS）研制出了高强度低介电Si3N4基复合陶瓷材料。研究了Si3N4加入量对复合材料力学和介电性能的影响,分析了该材料的显微结构特点。实验结果表明：通过加入27％Si3N4制备的氮化硅基复合材料,其室温抗弯强度（σRT）为366MPa,介电常数（ε）为5．2,介电损耗（tanδ）为9×10^-3。     

烧结温度对氮化硅陶瓷球显微结构和力学性能的影响

以α-Si3N4粉为原料,纳米级Y2O3和Al2O3为烧结助剂,采用气压烧结工艺制备氮化硅陶瓷球,研究了烧结温度对陶瓷球显微结构及力学性能的影响.结果表明,随着烧结温度的升高,陶瓷球的维氏硬度和压碎强度先提高后降低,断裂韧性不断提高.烧结温度为1780℃的陶瓷球综合力学性能最佳,其相对密度达到了99％,维氏硬度、断裂韧...     

Influence of injection temperature and pressure on the properties of alumina parts fabricated by low pressure injection molding (LPIM)

The quality of ceramics parts made by powder injection molding (PIM) method is influenced by a range of factors such as powder and binder characteristics, rheological behavior of feedstock, molding parameters and debinding and sintering conditions. In this study, to optimize the molding parameters, the effect of injection temperature and pressure on the properties of alumina ceramics in the LPIM process were thoroughly studied. Experimental tests were conducted on alumina feedstock with 60 vol% powder. Injection molding was carried out at temperatures and pressures of 70–100 °C and 0.1–0.6 MPa respectively. Results showed that increase in injection temperature and pressure and the resulting increase in flow rate leads to the formation of void which impairs the properties of molded parts. The SEM studies showed that injection at temperature of 100 °C results in evaporation of binder components. From the processing point of view, the temperature of 80 °C and pressure of 0.6 MPa seems to be the most suitable condition for injection molding. In addition, the effects of sintering conditions (temperature and time) on the microstructure and mechanical properties are discussed. The best final properties were found using injection molding under the above stated conditions, thermal debinding and sintering at 1700 °C during 3 h.     

Aetiology of Defects in Large Ceramic Moldings

This study is an attempt to identify the causes of defects that appear in large ceramic injection molded bodies after sintering. It asks the question: are such defects established at the injection molding stage or are they caused by the debinding process or by sintering? Moldings with ascending thickness were prepared using a mold cavity with replaceable tool faceplates. Control over pressure during solidification was compared by using conventional molding and a novel molding technique that uses an insulated sprue. The organic vehicle is polyoxymethylene, which can be displaced by catalytic degradation in the solid state. This is a shrinking unreacted core process with a clearly defined reaction boundary in which there is no provision for particle movement in the liquid state. This study tracks the development of defects at each stage and concludes that the defects apparent after sintering have their origin in injection molding, even though they do not mature until a later stage.     

陶瓷注射成型技术及其新进展

详细阐述了陶瓷注射成型技术的关键因素,全面介绍了国内外的新进展和动态,重点介绍了粉末共注成型、低压注射成型和微粉末注射成型等新技术。在此基础上评价和展望了该技术的发展前景。     

氧化锆陶瓷注射成形工艺研究

研究了氧化锆陶瓷粉末注射成形工艺过程，包括粘结剂的选择、喂料粉末装载量的确定、混炼工艺及混炼扭矩的研究，注射压力、注射温度、保压压力、模具温度、注射速度等注射成形工艺对成形坯质量的影响，以及溶剂脱脂温度、样品厚度、粉末粒度及形藐等对溶剂脱脂速率的影响及后续热脱脂工艺，扶得了一条优化的注射成形工艺路线。     

注射成型氧化铝陶瓷工艺研究

研究了氧化铝陶瓷注射成型工艺过程,包括粘结剂的选择、粉末装载量的确定及热脱脂工艺的研究。探讨了注射压力、注射温度和模具温度等注射成型工艺参数对试样性能的影响,得到了一条优化的氧化铝注射成型工艺路线。     

Effect of microcrystalline wax on the solvent debinding of the Sr-ferrite ceramics prepared by powder injection molding

Powder injection molding (PIM) opens new possibilities to process complex Sr-ferrite components for magnetic applications. In the present study, new binder system with the addition of microcrystalline wax (MW) was used for the Sr-ferrite powder injection molding. The optimum binder composition was determined based on rheological measurement, mircrostructure observation by SEM, thermal change by DSC and debinding process. The results indicated that MW with 10 vol.% addition in the binder system containing high density polyethylene (HDPE), paraffin wax (PW) and stearic acid (SA) decreases the defects of the green parts after solvent debinding because the distribution of the binder system between the Sr-ferrite particles becomes more homogeneous. Using the proper binder system containing MW, the defect-free and dense Sr-ferrite ceramics can be prepared after solvent and thermal debinding and sintering. Based on the experimental results, the effects of MW microcrystalline wax on the solvent debinding of the Sr-ferrite ceramics were detailed discussed.     

Supercritical Carbon Dioxide debinding in metal injection molding (MIM) process

The conventional debinding process in metal injection molding (MIM) is critical, environmentally unfriendly and time consuming. On the other hand, supercritical debinding is thought to be an effective method appropriate for eliminating the aforementioned inconvenience in the prior art. In this paper, supercritical debinding is compared with the conventional wicking debinding process. The binder removal rates in supercritical CO₂ have been measured at 333.15 K, 348.15 K, and 358.15 K in the pressure range from 20 MPa to 28 MPa. After sintering, the surface of the silver bodies were observed by using SEM. When the supercritical CO₂ debinding was carried out at 348.15 K, all the paraffin wax (71 wt% of binder mixture) was removed in 2 hours under 28 MPa and in 2.5 hours under 25 MPa. We also studied the cosolvent effects on the binder removal rate in the supercritical CO₂ debinding. It was found that the addition of non-polar cosolvent (n-hexane) dramatically improves the binder removal rate (more than 2 times) for the paraffin wax-based binder system. This paper is dedicated to Dr. Youn Yong Lee on the occasion of his retirement from Korea Institute of Science and Technology.