氧化锆陶瓷注射成型溶剂脱脂行为的研究

以氧化锆陶瓷粉体为研究对象,采用低毒性、低成本的煤油作为有机脱脂溶剂,研究了注射成型生坯的溶剂脱脂行为,探索了时间、温度、固相体积分数和粘结剂体系对脱脂速率的影响,分别讨论了各因素影响脱脂速率的机理.结果表明:脱脂速率随温度升高而升高,随时间的延长而降低;脱脂初期扩散是控制性环节,温度是影响反应速率的主要因素,脱脂后期溶解成为控制性环节,浓度差成为影响反应速率的主要因素;注射坯体固相体积分数越高,脱脂速率越慢,粘结剂最终脱除率越低;用部分植物油取代石蜡的蜡-油基复合型粘结剂注射坯体的脱脂速率快于传统蜡基型的注射坯体,最终脱脂率也高于传统型的蜡基注射坯体.     

注塑件变形分析

注塑件变形始于塑料的收缩,型腔中压力梯度、温度梯度以及剪切应力的客观存在导致了注塑件各部位收缩的不均一.本文分析了注塑成型过程中简单收缩、冷却、分子取向等因素对注塑件变形的影响.通过对实际零件的分析,阐述了模具设计中通过优化型腔设计、冷却系统设计、浇口设计来减小零件变形的具体方法.     

注射成型氟硅橡胶的应用

经过几十年的发展,注射成型氟硅橡胶已经具备良好的耐热性、耐寒性、耐高压性等特征,现已经广泛应用于化工、汽车、航天、石油、电子电器、医疗、机械等产业。对注射成型氟硅橡胶的性能进行详细阐述,并对它的用途进行分析总结。     

基于CAE的塑料注塑制品强度设计

全面阐释了影响塑料结构件强度的因素及机理，运用注塑过程仿真(CAE)技术和注塑件强度设计理论，以环形塑件和玻璃纤维增强塑件为例进行了分析，并对环形塑件进行了试验验证。结果表明：模具结构和注塑工艺对注塑件的强度有一定影响，而且数值仿真CAE技术对注塑件的强度设计有较好的预测能力，能够为实际注塑件结构设计提供更多的参考和建议。     

粉末注射成型金刚石制品的溶剂-热脱脂工艺

利用粉末注射成型技术对金刚石/铜基钎料粉末进行了注射成型实验,制备出了小型金刚石制品。采用溶剂–热脱脂二步脱脂工艺对金刚石制品进行脱脂处理。分析了溶剂脱脂过程中脱脂温度及脱脂时间对脱脂率的影响规律;利用扫描电子显微镜观测了不同溶剂脱脂时间下微观孔隙形成情况;考察了分别在H2和N2气氛下热脱脂效果。结果表明:采用正庚烷为脱脂溶剂时,溶剂脱脂温度越高、脱脂时间越长,溶剂脱脂率越大,在35℃脱脂2.5 h后,脱脂率达到了92.1%,金刚石制品形成了大量的连通孔隙。在600℃保温60 min热脱脂后,金刚石制品中的黏结剂已全部脱除,制品中未发现鼓泡、开裂、塌陷等缺陷,脱脂效果良好。在热脱脂过程中,H2气氛脱脂相对于N2气氛脱脂碳含量增大了0.05%,氧含量减少了0.13%,在H2中脱脂更利于后续烧结过程中金刚石制品的有效烧结。     

Study on the Accuracy of Injection Molded Plastic Gear with the Assistance of Supercritical Fluid and a Pressurized Mold

Plastic gears are lighter and less noisy compared to steel gears, and they can be easily shaped into diverse forms by the injection molding process. For this reason, plastic gears are widely used in industry. An extensive amount of research has been conducted on gear materials and methods of shaping plastic gears for durability and for broader applications. In this article, the focus is on producing a plastic gear shaping method incorporating the injection molding process.

The most important factor influencing the durability of a plastic gear is its accuracy. Unlike steel gears, the dimensions of plastic gears are subject to considerable change during formation, and this is due to certain conditions during the injection molding process and to the mold structure. The main causes of size variability here are the high viscosity of plastic and the shrinkage ratio of the resin. In our study, a supercritical fluid was used to reduce the viscosity of the plastic, and a pressurized mold was used to control the shrinkage ratio of the resin. Thus, production of an improved, more highly accurate plastic gear was achieved.     

注射速度对制品成型结晶形态的影响

以某平板塑件为例,以聚丙烯（PP）为实验材料,通过成型取样、X射线衍射实验及数据处理技术相结合的方法研究了注射速度对制品结晶形态的影响规律及影响效应。结果表明,在正常情况下,PP塑件的结晶类型主要为α、β两种晶型;制品的结晶度随注射速度的增大存在极点,呈现倒V字形的变化趋势;制品整体取向度与晶格畸变量具有类似的变化趋势,均随注射速度的增大而增大,而晶粒尺寸的变化则与注射速度呈现负相关性;注射速度对制品晶粒的影响最为显著,结晶度影响其次,影响显著性顺序依次为晶粒尺寸>结晶度>晶格畸变>取向度>晶型,对于本试样,最佳注射速度应控制在180 mm/s。     

Adhesion of Injection Molded PVC to Steel Substrates

Interactions occurring at the interface between injection-molded poly (vinyl chloride) (PVC) and steel substrates that were coated with thin films of aminosilanes were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The silane films were formed by adsorption of γ-aminopropyltriethoxysilane (γ-APS) or N-(2-aminoethyl-3-aminopropyl)trimethoxysilane (γ-AEAPS) from 2% aqueous solutions onto polished steel substrates. PVC was injection molded onto the silane-primed steel substrates and annealed at temperatures up to 170°C for times as long as 30 min. PVC was peeled off of the primed steel substrates using a 90° peel test and the substrate failure surfaces were thoroughly rinsed with tetrahydrofuran (THF) and distilled water to remove PVC and other compounds that were not strongly bonded to the substrates. The PVC failure surfaces were characterized by attenuated total reflection infrared spectroscopy (ATR) and PVC rinsed off of the substrate failure surfaces was characterized by transmission infrared spectroscopy. The resulting transmission and ATR spectra showed an absorption band near 1650 cm^?1 that was attributed to unsaturation in PVC. The substrate failure surfaces were characterized by XPS; curve-fitting of N(1s) and Cl(2p) high-resolution spectra showed the formation of amine hydrochloride complexes by protonation of amino groups of the silanes with HCl that was liberated from PVC during the onset of thermal dehydrochlorination. Furthermore, quaternization or nucleophilic substitution of labile pendent allylic chloride groups by amino groups on the silanes took place, thus grafting PVC onto the aminosilanes. It was determined that PVC that had β-chloroallyl groupings along its chains showed better adhesion with steel primed with aminosilanes and that generation of allylic chloride groups in PVC chains was the rate-limiting step in the reaction between PVC and aminosilane. Moreover, the effect of crosslinking of silane films on adhesion between PVC and aminosilane primed steel was investigated and it was concluded that interdiffusion of the polymer phase and the silane phase was also critical in obtaining good adhesion.     

注塑制品翘曲变形的研究进展

介绍了翘曲变形的分类、产生原因及表征方法,分析了影响翘曲变形的因素,包括成型材料、塑件结构、模具结构和工艺参数等,并介绍了计算机辅助工程技术在注塑制品翘曲变形分析中的应用及解决翘曲变形的方法。     

气体辅助注射成型聚苯乙烯制品取向研究

聚合物制品的收缩率可以间接地反映其分子链的取向行为。通过在不同退火温度下聚苯乙烯气体辅助注射成型制品表层和气道层收缩率的测量,研究其不同部位的收缩率。结果表明:表层区域的收缩率明显大于气道层区域的收缩率;在比较收缩率的基础上,探讨了非晶聚合物在气体辅助注射成型工艺过程中的取向机理。     

Adhesion of Injection Molded PVC to Steel Substrates

Interactions occurring at the interface between injection-molded poly (vinyl chloride) (PVC) and steel substrates that were coated with thin films of aminosilanes were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The silane films were formed by adsorption of γ-aminopropyltriethoxysilane (γ-APS) or N-(2-aminoethyl-3-aminopropyl)trimethoxysilane (γ-AEAPS) from 2% aqueous solutions onto polished steel substrates. PVC was injection molded onto the silane-primed steel substrates and annealed at temperatures up to 170°C for times as long as 30 min. PVC was peeled off of the primed steel substrates using a 90° peel test and the substrate failure surfaces were thoroughly rinsed with tetrahydrofuran (THF) and distilled water to remove PVC and other compounds that were not strongly bonded to the substrates. The PVC failure surfaces were characterized by attenuated total reflection infrared spectroscopy (ATR) and PVC rinsed off of the substrate failure surfaces was characterized by transmission infrared spectroscopy. The resulting transmission and ATR spectra showed an absorption band near 1650 cm^-1 that was attributed to unsaturation in PVC. The substrate failure surfaces were characterized by XPS; curve-fitting of N(1s) and Cl(2p) high-resolution spectra showed the formation of amine hydrochloride complexes by protonation of amino groups of the silanes with HCl that was liberated from PVC during the onset of thermal dehydrochlorination. Furthermore, quaternization or nucleophilic substitution of labile pendent allylic chloride groups by amino groups on the silanes took place, thus grafting PVC onto the aminosilanes. It was determined that PVC that had β-chloroallyl groupings along its chains showed better adhesion with steel primed with aminosilanes and that generation of allylic chloride groups in PVC chains was the rate-limiting step in the reaction between PVC and aminosilane. Moreover, the effect of crosslinking of silane films on adhesion between PVC and aminosilane primed steel was investigated and it was concluded that interdiffusion of the polymer phase and the silane phase was also critical in obtaining good adhesion.     

高密度聚乙烯薄壁件注射成型时的结晶特性研究

用Moldflow MPI5.0软件的Flow 3D模块仿真及同步热分析仪分析的方法,研究了熔体温度及注射速率对薄壁件注射成型时结晶特性的影响。结果表明,熔体温度为175、195、215 ℃时,在厚度为0.8 mm的高密度聚乙烯薄壁件的注射成型过程中,在流动方向上,浇口附近的剪切速率和熔融热焓远大于其他各处,且二者均随着与浇口间距离的增加而迅速降低;从距浇口1.5 mm处到制品末端,剪切速率稳定在2000～4000 s-1之间;从距浇口5 mm处至制品末端,熔融热焓的变化不明显;熔体温度为215 ℃时,制品的熔融热焓最高;随着注射速率的增加,浇口处的最大剪切速率亦增加。     

3D Printed Tooling for Injection Molded Microfluidics

Microfluidics have been used for several decades to conduct a wide range of research in chemistry and the life sciences. The reduced dimensions of these devices give them advantages over classical analysis techniques such as increased sensitivity, shorter analysis times, and lower reagent consumption. However, current manufacturing processes for microfluidic chips either limit them to materials with unwanted properties, or are not cost-effective for rapid-prototyping approaches. Here the authors show that inlays for injection moulding can be 3D printed, thus reducing the skills, cost, and time required for tool fabrication. They demonstrate the importance of orientation of the part during 3D printing so that features as small as 100 × 200 µm can be printed. They also demonstrate that the 3D printed inlay is durable enough to fabricate at least 500 parts. Furthermore, devices can be designed, manufactured, and tested within one working day. Finally, as demonstrators they design and mould a microfluidic chip to house a plasmonic biosensor as well as a device to house liver organoids showing how such chips can be used in organ-on-a-chip applications. This new fabrication technique bridges the gap between small production and industrial scale manufacturing, while making microfluidics cheaper, and more widely accessible.     

Edge-Crack Resistance Curves in Supercritical Ceramics

The growth of edge cracks in zirconia-reinforced ceramics is analyzed theoretically with the „supercritical” transformation model. The injection of an initial edge crack by a damage process is modeled in an approximate manner. Subsequent crack growth under the application of a remote tensiles stress models the evolution of the transformed region as the crack advances. For the range of initial crack sizes considered, „nominal” resistance curves depend strongly on a transformation-toughening parameter. The analysis may have a bearing on the indentation/bend method of testing fracture toughnesses.     

聚丙烯注塑件微观结构对性能的影响

讨论了聚丙烯注塑制品的微观结构形态,包括结晶、取向、残余应力、密度分布与制品收缩以及熔合缝等的形成及其对塑件宏观性能的影响。阐明了在注射成型工艺条件下形成的微观结构最终决定着制品的物理力学和使用性能。     

注塑制品翘曲变形的最显著影响因素

采用Moldflow进行了塑料制品注塑过程模拟实验,分析了模具温度、熔体温度、保压时间、保压压力、冷却时间、注射时间和速度/压力控制转换（V/P转换）对注塑制品翘曲的影响,从中确定影响最显著的注塑过程参数。首先按一次因子法进行实验,根据因子效应,各因子影响权重顺序为：保压时间>冷却时间>熔体温度>注射时间> V/P转换>保压压力>模具温度,其中熔体温度、保压时间、冷却时间、注射时间对制品的翘曲有明显影响;再采用田口实验方法对这4个因素进行模拟实验,用L9（34）正交表设计实验,根据实验数据计算信噪比以评判影响因子的权重,由翘曲信噪比、体积收缩率信噪比和缩痕指数信噪比三方面分析,发现熔体温度对制品翘曲的影响最为显著。     

基于熔体压力的注塑制品性能研究

利用脉动压力诱导注射成型装置对金属粉末/聚合物体系及低密度聚乙烯(LDPE)进行实验研究.实验结果表明:脉动压力的引入提高了金属粉末/聚合物体系注塑制品的致密性,制品密度提高;随着活塞杆振动振幅/频率的增大,低密度聚乙烯注塑制品力学性能提高,注塑试样熔融峰变宽,熔点向高温方向移动.     

高密度聚乙烯平板翘曲变形实验研究

研究了两种模具、七种成型工艺参数与高密度聚乙烯平板翘曲变形之间的关系。归纳实验现象,总结各种因素对翘曲变形的影响规律,并探讨翘曲变形成型机理。结果发现：结晶型HDPE平板非常容易发生翘曲变形;模具浇口的形状、大小和位置对HDPE平板翘曲变形的影响非常大;浇口和塑料类型不同,各个工艺参数对翘曲变形的影响程度也不同。