应用于紫外DLP-3D打印系统的低体积收缩率和高固化速度的光敏树脂研究

在基于数字光处理(DLP)技术的3D打印过程中,紫外波段光敏树脂的光固化性能将直接影响工件的打印精度、速度和形貌。选用改性双酚A型环氧丙烯酸酯和脂肪族聚氨酯丙烯酸酯作为低聚物,配合三丙二醇类二丙烯酸酯(TPGDA)和乙氧化三羟甲基丙烷三丙烯酸(TMPEO3TA)作为稀释剂和自由基-阳离子杂化体系作为光引发剂,配置了面向405 nm波段的DLP-3D打印系统的混杂型光敏树脂。研究结果表明,所制备的光敏树脂的体积收缩率控制在2.3%内,室温下的粘度为244 MPa·s,固化速度缩短到0.063 mm/s。相比较于其它国内外光敏树脂,该树脂整体表现出优良的力学性能。在此基础上,通过在树脂中掺杂1%左右的纳米ZnO颗粒助料,材料的力学性能得到进一步改善,体积收缩率降低至2.1%。这一混杂型光敏树脂将可有望应用于对精度要求较高的光电子器件的DLP-3D打印中。     

混杂光固化3D打印树脂固化动力学性能

以环氧树脂(EPON828)和聚氨酯丙烯酸酯(RJ429)为基础树脂,采用自由基-阳离子混杂光固化体系来制备可用于3D打印的混杂光固化树脂,研究固化过程中自由基和阳离子光引发剂的种类、质量配比和加入量对光固化树脂固化动力学及其力学性能与成型精度的影响。结果表明:阳离子光引发剂Gencure 842和自由基光引发剂Doracur 1173为最佳复配引发剂,最佳质量比为0.75∶1,最优加入量为6.0%(质量分数);环氧树脂828和聚氨酯丙烯酸酯429的最佳质量比为1∶1,混杂光固化树脂的黏度为50.5Pa·s;光固化制品的拉伸强度和冲击强度分别为6.60MPa和8.28kJ·m~(-2),体积收缩率和翘曲度分别为-3.986%和3.62%,满足3D打印光敏树脂的成型要求。     

碳纤维增强碳化硅三维网状多孔陶瓷复合材料的制备

以3D打印多孔PLA结构为模板,采用聚碳硅烷先驱体浸渍裂解法(PIP),在1 250℃,氩气氛围下烧结得到碳纤维增强碳化硅三维网状多孔陶瓷复合材料。采用XRD、SEM和万能力学试验机等对碳纤维增强碳化硅三维网状多孔陶瓷复合材料进行了表征。结果表明,由β-SiC和C两种晶相组成,随着3D打印件的骨架直径增大,所制备的3D-Cf/SiC多孔陶瓷复合材料的孔隙率逐渐减小,而其表观密度、骨架密度、压缩强度、导热系数逐渐增加;当3D打印件的骨架直径从1.0mm增加到2.5mm时,3D-Cf/SiC的孔径从1.0mm增加到2.5mm,孔隙率从63%增加到82%,表观密度和骨架密度分别从0.85g/cm3降低至0.45g/cm3,1.52g/cm3降低至0.92g/cm3,压缩强度从8.00 MPa降低至4.20 MPa,导热系数从2.00 W/(m·K)降低至1.20 W/(m·K)。     

树脂包覆球形SiO2颗粒制备3D打印用陶瓷/树脂复合粉体

采用球形致密的SiO₂微米颗粒制备用于3D打印的陶瓷/树脂复合粉体, 并对粉体的固化和烧结性能进行了研究。结果显示, 随着温度升高或固体含量的增加, 包覆介质的粘度逐渐增大, 最佳树脂浓度为27wt%。均匀包覆的陶瓷/树脂复合粉体具有良好的分散性、流动性(25 (s/50 g))和较大的堆积密度(45.0%)。球形颗粒堆积形成的贯通孔道和球形颗粒表面均匀的吸附能对均匀包覆过程起到了至关重要的作用。包覆层的厚度(1.1~3.7 μm)可以通过调节抽滤过程的负压进行精确控制。由于颗粒之间形成了树脂颈部, 使制备的粉体具有很好的固化强度, 固化的陶瓷生胚经1250 ℃烧结后获得了性能优异的陶瓷: 压缩强度为10.2 MPa, 弯曲强度为2.7 MPa, 烧结收缩仅5%。上述结果表明, 复合粉体在3D打印产业上具有良好的应用前景。     

树脂包覆球形SiO_2颗粒制备3D打印用陶瓷/树脂复合粉体（英文）

采用球形致密的SiO2微米颗粒制备用于3D打印的陶瓷/树脂复合粉体,并对粉体的固化和烧结性能进行了研究。结果显示,随着温度升高或固体含量的增加,包覆介质的粘度逐渐增大,最佳树脂浓度为27wt%。均匀包覆的陶瓷/树脂复合粉体具有良好的分散性、流动性(25 (s/50 g))和较大的堆积密度(45.0%)。球形颗粒堆积形成的贯通孔道和球形颗粒表面均匀的吸附能对均匀包覆过程起到了至关重要的作用。包覆层的厚度(1.1～3.7μm)可以通过调节抽滤过程的负压进行精确控制。由于颗粒之间形成了树脂颈部,使制备的粉体具有很好的固化强度,固化的陶瓷生胚经1250℃烧结后获得了性能优异的陶瓷:压缩强度为10.2 MPa,弯曲强度为2.7 MPa,烧结收缩仅5%。上述结果表明,复合粉体在3D打印产业上具有良好的应用前景。     

酚醛树脂粘结钕铁硼磁体温压制备技术研究

用温压成型工艺制备了酚醛树脂粘结钕铁硼磁体,通过对磁体密度、剩磁、矫顽力、磁能积和抗弯强度的分析,研究了耦联表面处理对磁粉抗氧化性能的影响及成型工艺对磁体性能的影响.结果表明:偶联处理可以明显提高磁粉的抗氧化能力;在压力为620MPa,温压温度为180℃且不进行二次固化条件下获得了性能最佳的磁体,其密度为6.12g/cm3,抗弯强度为59.25MPa,剩磁为0.6824T,内禀矫顽力为730kA/m,最大磁能积为78.2kJ/m3.     

UV-3D打印材料研究进展

UV-3D打印作为增材技术新的发展方向,具有设计自由,节约材料以及快速成型等优点,被广泛研究。本文通过分析立体光刻技术(SLA),数字光处理技术(DLP)和UV直写技术等,并研究了UV技术在3D打印领域的应用与发展。然后分析UV-3D打印常用的一些材料,包括环氧树脂和丙烯酸树脂以及其发展现状。最后通过介绍UV技术在3D打印的应用现状提出发展对策。     

高氯酸铵粒径对3D打印含能树脂药柱燃烧性能的影响

为了改善光敏树脂的燃烧性能,通过添加不同粒径和含量的高氯酸铵（AP）作为氧化剂,利用3D技术打印出含能树脂药柱。考察了AP在光敏树脂中的分散性及燃烧性能。结果表明:粒径为5.28 μm的AP在光敏树脂中的分散性最好;打印成型的含能树脂药柱燃速最快,残渣率最小。与打印成型的纯树脂药柱相比,该药柱的燃速提高了14倍,残渣率降低了94.30%。随着AP的质量分数从10%增至50%,药柱燃烧性能明显改善;当AP的质量分数为50%时,含能树脂药柱的燃速最高,残渣率最小,分别为1.05 mm/s和1.10 %。差热分析表明,含粒径为5.28 μm的AP的含能树脂药柱温度峰值出现最早,放热量最高。     

核用氧化锆耐火材料光固化增材制造工艺及性能研究

目的 为提高精密铸造效率，缩短制模周期，利用光固化增材制造技术制备适合活泼金属铸造用的ZrO2陶瓷模具。方法 将光敏树脂与纳米级ZrO2陶瓷粉体混合得到具有光固化性能的陶瓷浆料，采用数字光投影增材制造设备对陶瓷浆料进行逐层曝光，揭示不同固含量对陶瓷浆料固化性能的影响规律;利用光固化3D打印制备ZrO2陶瓷生坯，经过干燥、脱脂和烧结处理，获得所需陶瓷样件，并对成型后的ZrO2陶瓷进行微观组织表征、力学性能(压缩和弯曲)和抗热震性能测试。结果 在相同固化强度的基础上，随着ZrO2陶瓷浆料固含量的增加，固化深度逐渐减小，固化宽度无明显变化。光强度越高，固化深度和宽度均越大。选用固含量(体积分数)为50%的陶瓷浆料，在紫外光波长405 nm、光强度25 mW/cm²、曝光时间2 000 ms、层厚30 μm的工艺条件下制备ZrO2陶瓷生坯，经过最高温度450 ℃脱脂和最高温度1 525 ℃烧结处理，获得了无变形和开裂的ZrO2陶瓷样件。陶瓷的压缩和弯曲强度分别达到2 943、833 MPa，与等静压工艺制备的陶瓷强度相当，优于其他3D打印工艺制备的陶瓷产品。光固化3D打印ZrO2陶瓷在800 ℃下热震10次和1 400 ℃下热震5次后才开始出现局部细小裂纹，满足核冶金铸造使用要求。结论 利用光固化3D打印技术可制备致密度大、强度高、抗热震性能良好的陶瓷模具，是一种工艺简单、效率高的新型陶瓷加工工艺，在核工业领域具有重要的应用前景。     

光敏树脂和光固化3D打印技术的发展及应用

3D打印技术是近些年迅猛发展的一种快速制造技术,光固化3D打印技术及光敏树脂为3D打印中最为成熟的部分。介绍了光敏树脂的组成及各组分的作用,简述了几类光固化技术,并概述了光敏树脂及光固化3D打印技术的研究进展和应用,最后指出光固化3D打印技术正朝着材料多样化、高精度、高速率的方向迅速发展。     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

重塑标准推行格局 推动LED照明的普及（英文）

正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.     

Chinese Experts Contribute to ISO＇s New Toy Standards

正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.     

中国质量(北京)大会(英文)

正Themed on"quality,innovation,development",the first China Quality Conference(Beijing)was held in the Great Hall of the People on September 15.Chinese Premier Li Keqiang delivered an important speech at the conference.State Councilor Yang Jing and Wang Yong attended the conference with over 600 domestic and international representatives from foreign,regional and international quality organizations     

National Working Meeting on Land and Resources Standardization

正The National Working Meeting on Land and Resources Standardization was held in Beijing on July 15,2014.Wang Min,the Deputy-Minister of the Ministry of Land and Resources,and Yin Minghan,the Chief-Engineer of SAC addressed the meeting.Representatives from relevant competent departments and technical committees were present.The meeting aims to summarize work,discuss existing problems and make clear working thoughts,promoting standardization work of land and resources to a new level.Wang Min pointed out that the standardization work of land and resources should be centered on the basic principles of"protecting land and resources dutifully,intensively and economically utilizing land and resources,and making all-out efforts to safeguard the public’s rights and interests",highlighted the