Effect of light attenuation on polymerization of ceramic suspensions for stereolithography

Weak bonding strength between interlayers can seriously affect the quality of ceramic parts manufactured by stereolithography. Therefore, the possibility of using chemical bonds to strengthen the adhesion within these parts and the extent to which may be effective are of interest. Thus, a multi-exposure model was built to illustrate the state of this interface. The secondary conversion of a cured layer defined as conversion rate increment caused by decayed ultraviolet (UV) light in a subsequent exposure was selected to represent the extent of a chemical bond. The level of UV light attenuation occurred when travelling through a suspension layer was determined using the Attenuation Law. When decayed light illuminated a cured layer, it underwent further photopolymerization, which was detected by temperature change. The secondary conversion was affected by parameters including the incident energy dose and the propagating length. Optimization of these parameters helped to achieve higher chemical bond ratio.     

光固化法快速成型技术中的紫外光源

本文简要分析了快速成型技术中光固化法的成型机理，给出了固化深度，固化线宽公式，据此对可适用的紫外光源进行了分析和比较。指出应用大功率的紫外固体激光器和普通的远紫外汞氙灯将成为快速成型技术的发展趋势。     

煤系高岭土光固化浆料的流变性能EI北大核心CSCD

基于光敏树脂体系制备煤系高岭土光固化浆料,采用流变仪对浆料的流变性能进行表征,研究分散剂和增塑剂加入量对浆料流变性能的影响。结果表明:油酸作为分散剂具有降低浆料黏度的效果,当油酸加入量为高岭土粉体的1%(质量分数)时浆料的黏度最小,在该条件下40%(体积分数)高岭土浆料的黏度为49.56 Pa·s。加入增塑剂PEG-300能够进一步降低浆料的黏度,浆料黏度随着增塑剂加入量的增加而减小,当增塑剂加入量为光敏树脂的20%(质量分数)时40%(体积分数)高岭土浆料的黏度下降为19.77 Pa·s,已经能较好地满足浆料涂布的要求。采用流变性能优化的浆料进行光固化成形,经过排胶、烧结后得到复杂形状的高岭土陶瓷件。     

Nanomaterials for 3D Printing of Polymers via Stereolithography: Concept,Technologies, and Applications

Stereolithography (SLA) is an additive manufacturing method with one of the highest accuracies (down to 100 nm) of all solid freeform techniques and has been used in various areas, such as medicine, automotive, aerospace, electronics, and others. However, most resins available nowadays are derived from petroleum. Its toxicity, low biocompatibility, and growing environmental concerns are limiting its application. This review discusses the development of biobased and biocompatible materials for different SLA processes as well as the usage of nanocomposites to increase their applicability. A comprehensive overview of the SLA technologies, photopolymerization chemistry, and resin properties are also provided. Finally, various examples using different types of materials are explored, to show the current and future capabilities of the SLA technique.     

Development of a Hybrid Photopolymer for Stereolithography

1 IntroductionRapid Prototyping (RP) was developed as a newmanufacture technique and considered a significant break-through in the field of manufacturing in the past 20years[1-4].The principle of RPis based on layer additivefabrication. Firstly, a three-dimensional object modelfromcomputer-aided design (CAD) is divided into manythinlayers by delaminatingsoftware .Thetwo-dimensionaldata of eachthinlayer control alaser beam,whichirradi-ates many materials like resin point-by-point ,and solid…     

光固化成型中液位控制系统的研究

光固化快速成型是一种新型的加工方法,成型精度是零件加工的关键,成型过程中,树脂液位波动会影响成型精度及制作过程的进行.针对光固化成型(SL)系统中树脂液位波动的问题,本系统中采用了一种通过激光非接触反射测量的方式检测并控制液位的方法.实践表明:采用液位控制后,液位波动可以很好的控制,完全能够满足整机系统对液位控制0.003～0.014mm的精度要求.     

基于层面轮廓凸分解的光固化选区环形扫描路径的生成算法

提出了一种新的基于层面轮廓凸分解的光固化选区环形扫描方式及其扫描路径生成算法，它通过对分层后的截面轮廓进行去除内环、凹多边形凸分解等处理，获得若干形态质量好的凸多边形子区域，再对各子区域进行Vomnoi图划分进而实现环形扫描路径规划，然后采用隔区扫描的方式实现层面轮廓的选区环形扫描。实际应用表明：这种扫描方式可有效地减小零件翘曲变形并提高成形效率。     

Stabilization of tricalcium phosphate slurries against sedimentation for stereolithographic additive manufacturing and influence on the final mechanical properties

Ceramic parts manufactured by lithography‐based ceramic manufacturing (LCM) excel in resolution and surface quality. The material for LCM is a photosensitive ceramic particle‐filled slurry which needs to have homogeneous properties over time and during each processing step. The goal of this study was to use “mechanical” stabilization for a tricalcium phosphate‐filled slurry done by increasing slurry viscosity, solids loading, or inducing thixotropic behavior. The modified slurries were compared with a nonstable reference slurry. While all methods lead to increased storage stability, only the stabilized slurry with 0.5 wt% fumed silica is stable during the printing process.     

特种微型机械加工技术

综述微型机电系统/微型机械的三维形状加工及极限尺寸加工的研究开发现状.相对硅微细加工和LIGA工艺,不采用掩膜版的特种微细加工技术,如微细激光成型、微细电火花加工以及微细机械加工等近年来取得较大进展,在三维微小机械结构成型上有独到优势;同时扫描隧道显微加工技术的开发将微型机械向极限尺寸领域推进.微型机电系统/微型机械的长足发展有赖于融合已有先进技术和交叉学科思想的微型机械加工技术的进一步研究开发.