期刊文献+
共找到384篇文章
< 1 2 20 >
每页显示 20 50 100
Comparing the Efficiency of Manual and Electronic Tender Document Preparation: Cost and Time Context
1
作者 Md. Abdur Rashid Mohammad Shorif Uddin 《Intelligent Information Management》 2022年第6期195-201,共7页
In Bangladesh, both manual and e-GP system is used to perform public procurement. Before tender publication, tender documents have to be prepared by the Procurement Entities (PEs). The problem is that the manual tende... In Bangladesh, both manual and e-GP system is used to perform public procurement. Before tender publication, tender documents have to be prepared by the Procurement Entities (PEs). The problem is that the manual tendering system involves more cost and time in preparing tender documents. The study’s purpose is to compare now the efficiency of tender document preparation in the manual system with the e-GP system. This study tests the cost and time involved in tender document preparation, both manual and e-procurement tenders. Sample data was collected from the 11 RHD zones. Structured survey questionnaires were used to collect primary data from the PE officers of RHD. A hypothesis test was performed using the model of independent samples t-test. The test results indicated that e-Procurement tender document preparation costs and time were less than manual tendering. Academicians, researchers, PE officers, and policymakers will benefit from the study’s conclusions. 展开更多
关键词 tender Document Preparation Cost tender Document Preparation Time E-PROCUREMENT T-TEST E-GP System Public Procurement RHD
下载PDF
Comparing the Cost and Time of Tender Opening Committee Report Preparation for Manual and E-Procurement Tenders in the Roads and Highways Department of Bangladesh
2
作者 Md. Abdur Rashid Mohammad Shorif Uddin 《Open Journal of Applied Sciences》 2022年第3期336-345,共10页
Bangladesh’s public procurement system has been traditional, i.e., a manual tendering system, under the legislative guidance of PPA-2006 and PPR-2008. Manual tendering has long been a source of concern for public pro... Bangladesh’s public procurement system has been traditional, i.e., a manual tendering system, under the legislative guidance of PPA-2006 and PPR-2008. Manual tendering has long been a source of concern for public procurement agencies regarding tender opening related to cost and time. To resolve this challenge and make the dream of a Digital Bangladesh a reality, the Government of Bangladesh launched the e-Procurement system in 2011 under the flagship of e-GP Guidelines. Following the successful pilot testing conducted under the umbrella of the CPTU, all public PEs are attempting to implement electronic procurement tenders. This study aims to examine the cost and time involved in preparing Tender Opening Committee (TOC) Reports for manual and e-procurement tenders in Bangladesh’s Roads and Highways Department. A mixed-method was used to collect data from the population of 11 RHD zones, including KII and primarily survey questionnaires. The independent samples t-test was used to compare data and hypothesis tests from two groups using SPSS software. The results indicated that e-Procurement tendering, tender opening preparation costs and time were more efficient than manual tendering. Academicians, students, practitioners, researchers, and policymakers will benefit from the study’s conclusions. Additionally, the government will be urged to improve policies such as the PPA 2006, the PPR 2008, and the 2011 e-GP Guideline. 展开更多
关键词 e-GP Guideline 2011 E-PROCUREMENT tender Opening Committee Report Preparation t-Test TOC Meeting
下载PDF
Effect of Preparation Method on Surface Area and Crystalline Form of CeO_2-ZrO_2 Solid Solution 被引量:1
3
作者 王晓红 郭耘 +4 位作者 卢冠忠 郭杨龙 王筠松 张志刚 刘晓晖 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第6期763-765,共3页
The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface are... The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m^2·g^(-1), and that calcined at 900 ℃ for 6 h is 88 m^2·g^(-1). The sample with tetragonal symmetry Ce_(0.5)Zr_(0.5)O_2 phase has a higher stability. 展开更多
关键词 reverse microemulsion method PREPARATION CeO_2-ZrO_2 solid solution high surface area crystalline form rare earths
下载PDF
PREPARATION AND MORPHOLOGY OF ISOTACTIC POLYPROPYLENE WITH HIGH CONTENT OF β CRYSTALLINE FORM
4
作者 黄美荣 李新贵 +1 位作者 戚慰先 方柏容 《Journal of China Textile University(English Edition)》 EI CAS 1994年第1期31-38,共8页
Isotactic polypropylene (iPP) with high content of ~ crystalline form was prepared by adding a series of new p form nucleators. The spherulites and morphology of//farm iPP (//-iPP) were investigated by wide-angle X-ra... Isotactic polypropylene (iPP) with high content of ~ crystalline form was prepared by adding a series of new p form nucleators. The spherulites and morphology of//farm iPP (//-iPP) were investigated by wide-angle X-ray diffraction(WAXD), polarizing microscope (PLM), scanning electron microscope (SEM) and small-angle light scattering (SALS). WAXD experimental results indicate that the amount of p form in iPP (K_x) increases with increasing /~ nucleator content from zero to 0.07 wt% or crystallization temperature T_c from 20 to 120℃ and that the highest K_x value is up to 0.95. PLM observations suggest that p spherulites exhibit bright color and that their Maltese Crosses display some concentric banding of a rather spiky, jagged character. Their !amellae are smooth and relaxed layer-plate like structure by SEM and their SALS H_v patterns arc four-petalled. 展开更多
关键词 ISOTACTIC polypropylene preparation spherulite MORPHOLOGY β CRYSTALLINE form β nucleator
下载PDF
New Approach for Isolation of Individual Caseins from Cow Milk by the Preparative Electrophoresis
5
作者 Andrii V. Iukalo 《Advances in Biological Chemistry》 2014年第6期382-387,共6页
This paper carried out a comparative analysis of different types of electrophoretic systems which were used for the analysis of casein complex from cow milk (polyacrylamide gel electrophoresis: for the neutral and aci... This paper carried out a comparative analysis of different types of electrophoretic systems which were used for the analysis of casein complex from cow milk (polyacrylamide gel electrophoresis: for the neutral and acidic native conditions, in gradient variant, the presence of sodium dodecyl sulphate or with including urea). Taking into attention the separation efficiency, complexity of electrophoretic system, the impact of system components, we have selected the anode system of the homogeneous gel in the presence of urea as the basis for the preparation of casein fractions. It also changed the composition and the structure of the electrophoretic apparatus. The changes allow purification of casein fractions up to several grams during one stage of treatment (for 5 hours). The purified casein fractions were tested for the homogeneity and have been recommended for using in the biomedical researches, including the processes of the formation of the bioactive peptides. 展开更多
关键词 CASEIN ISOLATION INDIVIDUAL forms ELECTROPHORESIS PREPARATIVE
下载PDF
Recycling of waste residue in aluminum production process
6
作者 ZHANG Guo-fu LIU Ling-ling +1 位作者 PENG Liang YE He-lin 《Journal of Chemistry and Chemical Engineering》 2009年第6期63-64,共2页
The preparation of crystal form of Al(OH)3 from the deposited residues of anodizing lines in the process of producing aluminum was studied. Alkali is used to dissolve the residue, and then blow CO2 is bellowed in, f... The preparation of crystal form of Al(OH)3 from the deposited residues of anodizing lines in the process of producing aluminum was studied. Alkali is used to dissolve the residue, and then blow CO2 is bellowed in, finally a kind of useful crystal Al(OH)3 is accessed by hydrolysis. The yield of the crystal Al(OH)3 was affected by temperature, pH and flow rate of CO2. The experimental results showed that under constant stirring, the optimized conditions was to control the temperature of 75-85℃, pH 7.5-9.0, CO/flow rate 60-80 mL/min. Using this method, the purpose of recovering valuable resources of Al, cleaning up the environment, and recycling of the by-product of Na2CO3 was achieved. It was of good economic and social benefits. 展开更多
关键词 auminum residue akali dissolved method preparation crystal form of Al(OH)3
下载PDF
蕲艾油-β-环糊精包合物膜剂的制备及工艺优化
7
作者 肖新才 梁云靖 洪宗国 《中南民族大学学报(自然科学版)》 CAS 2024年第5期614-618,共5页
为了提高挥发油在制剂中的生物利用度,采用β-环糊精对挥发油进行包合,再以羧甲基纤维素钠作为成膜材料,考察蕲艾油-β-环糊精包合物膜的最佳工艺.用饱和水溶液法制备蕲艾油-β-环糊精包合物,以外观评价、膜性质、脱模性能和贴肤度作为... 为了提高挥发油在制剂中的生物利用度,采用β-环糊精对挥发油进行包合,再以羧甲基纤维素钠作为成膜材料,考察蕲艾油-β-环糊精包合物膜的最佳工艺.用饱和水溶液法制备蕲艾油-β-环糊精包合物,以外观评价、膜性质、脱模性能和贴肤度作为表征评价指标,通过正交试验考察蕲艾油用量、β-环糊精用量、羧甲基纤维素钠浓度以及甘油用量对成膜工艺的影响.结果:蕲艾油-β-环糊精包合物膜最佳成膜工艺为:蕲艾油用量为1.5 mL、β-环糊精用量为10 g、羧甲基纤维素钠∶去离子水为1∶20(W/V,g·mL^(-1))、甘油用量为6 mL,用去离子水定容至100 mL.结论:优选得到的成膜工艺简单、稳定、可行,为该剂型的后续开发奠定基础. 展开更多
关键词 蕲艾油 Β-环糊精 羧甲基纤维素钠 制备 工艺优化 成膜工艺
下载PDF
航空发动机涡轮叶片热障涂层的现状与发展 被引量:1
8
作者 高玲玲 李瑞勤 《兵器材料科学与工程》 CAS CSCD 北大核心 2024年第4期121-129,共9页
热障涂层的研究对提高航空发动机涡轮叶片的工作效率和服役时间具有重要意义。本文重点介绍了热障涂层的结构、材料分类、制备及后处理技术、失效机制方面的研究现状,并对其未来发展进行了展望。高熵陶瓷材料等新型陶瓷材料因其优异的... 热障涂层的研究对提高航空发动机涡轮叶片的工作效率和服役时间具有重要意义。本文重点介绍了热障涂层的结构、材料分类、制备及后处理技术、失效机制方面的研究现状,并对其未来发展进行了展望。高熵陶瓷材料等新型陶瓷材料因其优异的热稳定性及综合力学性能,具有良好的应用前景。激光表面改性技术具有效率高、形变小、局部选区处理等优势,可进一步提高热障涂层的安全可靠性。后续热障涂层的研究将聚焦高熵陶瓷材料、功能梯度材料等的研究及应用,充分采用数值分析及建模等深入研究涂层的失效与防护机制,为航空发动机涡轮叶片的发展奠定基础。 展开更多
关键词 航空发动机 涡轮叶片 涂层材料 涂层制备 后处理技术 失效机制
下载PDF
4种机用镍钛器械预备树脂模拟弯曲根管成形能力比较
9
作者 梁昭璜 张瑶 《上海口腔医学》 CAS 2024年第1期54-58,共5页
目的:比较4种机用镍钛器械预备树脂模拟弯曲根管的成形能力。方法 :40个单弯树脂模拟根管随机分成为4组,每组10个,采用4种机用镍钛器械(ProTaper、HyFlex EDM、WaveOne Gold和Reciproc Blue)进行根管预备,分别记为A组、B组、C组和D组。... 目的:比较4种机用镍钛器械预备树脂模拟弯曲根管的成形能力。方法 :40个单弯树脂模拟根管随机分成为4组,每组10个,采用4种机用镍钛器械(ProTaper、HyFlex EDM、WaveOne Gold和Reciproc Blue)进行根管预备,分别记为A组、B组、C组和D组。比较4组预备时间,经计算机图像分析软件对预备前后根管图像进行分析,记录4组根管预备时间及根管弯曲度、弯曲半径的变化情况。以根尖为圆心,1~10 mm分别为半径,作同心圆弧线,检测点即重叠根管交点,记录不同检测点的根管内外侧壁树脂去除量与中心定位力。采用SPSS 20.0软件包对数据进行统计学分析。结果:A组根管预备时间显著长于B、C和D组(P<0.05),但4组根管弯曲度、弯曲半径变化无显著差异(P>0.05)。C组检测点至根尖孔距离5、6、8、9、10 mm的根管内侧壁树脂去除量显著低于A、B和D组(P<0.05),C组检测点至根尖孔距离5、6、7、9、10 mm的根管外侧壁树脂去除量显著低于A、B和D组(P<0.05),A组检测点至根尖孔距离1、2、3、4、6、7、8、9、10 mm的根尖偏移显著大于B、C和D组(P<0.05)。结论:4种器械中,ProTaper根尖偏移最大,HyFlex EDM、WaveOne Gold和Reciproc Blue根管成形能力相对更好。 展开更多
关键词 根管预备 机用镍钛器械 成形能力 中心定位力
下载PDF
膏方制备及对改善患者服药依从性的探讨 被引量:1
10
作者 吴佳慧 杨迪 吴书平 《中国中医药现代远程教育》 2024年第3期165-168,共4页
膏方是将药材反复煎煮后,去掉药渣,将药液浓缩,再添加胶类、糖类等药料反复熬制的一种中药剂型,结合患者的疾病特点及体质特点,“因人处方、因人制宜”,保持鲜明的个性化治疗特点。膏方在制备上需要更加规范的准备及制作过程,以便保证... 膏方是将药材反复煎煮后,去掉药渣,将药液浓缩,再添加胶类、糖类等药料反复熬制的一种中药剂型,结合患者的疾病特点及体质特点,“因人处方、因人制宜”,保持鲜明的个性化治疗特点。膏方在制备上需要更加规范的准备及制作过程,以便保证质量与功效,且在辅料、细料的选择上也有自己的特色。它的制备过程包括审方、调配、浸泡、煎煮、浓缩、收膏、凉膏等。文章从膏方制备过程中的注意事项及膏方改善患者服药依从性等方面进行探讨,为膏方的制备提供详细参考,对推动膏方的普及与发展具有一定的研究意义。 展开更多
关键词 膏方 中医药剂型 《五十二病方》 服药依从性
下载PDF
《本草图经》药物剂型分析及对现代制剂的启示
11
作者 张晓俊 杨友瑞 +1 位作者 杨红霞 黄泽豪 《亚太传统医药》 2024年第3期198-201,共4页
目的:通过分析宋代药物剂型的应用状况,探究我国药物制剂的发展历程。方法:对北宋本草著作《本草图经》中相关中药剂型数据进行统计与分析。结果:《本草图经》中明确记载的药物剂型,主要有散剂、丸剂、膏剂、丹剂这传统的四大剂型,其中... 目的:通过分析宋代药物剂型的应用状况,探究我国药物制剂的发展历程。方法:对北宋本草著作《本草图经》中相关中药剂型数据进行统计与分析。结果:《本草图经》中明确记载的药物剂型,主要有散剂、丸剂、膏剂、丹剂这传统的四大剂型,其中散剂最多(总计142种),丸剂其次(总计94种)。剂型的统计还呈现出一些规律:(1)植物药中,草类以丸剂为主,散剂次之;木类以膏剂为主;果部、菜部和米部以散剂为主;本经外草类与本经外木蔓类以散剂为主,其中均出现了贴剂的记载。(2)矿物药中,因其药物特殊性,主要以丹剂为主。(3)动物药中禽兽部和鱼虫部,主要以散剂为主,丸剂次之。(4)部分药物可适用于多种剂型,共有35种药适用于2种以上剂型,3种药适用于3种以上剂型。结论:《本草图经》药物剂型不仅反映了宋代以前中药传统剂型的应用状况,对现代药物制剂的古为今用、临床运用等具有较好的启示。 展开更多
关键词 《本草图经》 药物剂型 中药 现代药物制剂
下载PDF
浅谈工程投标书的编制
12
作者 何耀永 黄雨晴 苏荧荧 《工程建设与设计》 2024年第15期261-265,共5页
结合某污水处理站工程EPC总承包项目,对工程投标书的编制情况进行了分析和讨论。从标书编制工作人员和办公设备的配备两方面介绍标书编制情况,分析标书编制出现的问题,如填写信息不正确、投标文件内容不完整、人员证件没有及时更新、投... 结合某污水处理站工程EPC总承包项目,对工程投标书的编制情况进行了分析和讨论。从标书编制工作人员和办公设备的配备两方面介绍标书编制情况,分析标书编制出现的问题,如填写信息不正确、投标文件内容不完整、人员证件没有及时更新、投标文件格式不规范、施工组织设计不合理等,针对这些问题分析产生问题的原因,并提出相应的预防和解决措施。 展开更多
关键词 工程投标书 编制 问题 措施
下载PDF
眼用微片的研究进展
13
作者 鞠玲玲 许蕾 +1 位作者 侯铁强 朱希强 《食品与药品》 CAS 2024年第5期I0012-I0015,共4页
微片是一种新型的微型固体片剂,具有刺激性小、患者依从性高、作用时间长、生物利用度高等优点。眼用微片作为微片的一类,既可避免频繁给药,又可提高患者舒适度。微片制剂是目前研究的热点,眼用微片更是具有广阔的研究前景。本文主要阐... 微片是一种新型的微型固体片剂,具有刺激性小、患者依从性高、作用时间长、生物利用度高等优点。眼用微片作为微片的一类,既可避免频繁给药,又可提高患者舒适度。微片制剂是目前研究的热点,眼用微片更是具有广阔的研究前景。本文主要阐述了眼用微片的特点和近年来国内外眼用微片的相关研究,并从多角度对眼用微片的影响因素及研究前景等进行总结叙述。 展开更多
关键词 微片 眼用制剂 缓控释制剂 新剂型药物
下载PDF
水凝胶微针的进展
14
作者 万开龙 宋信莉 +4 位作者 沈丽 杨小双 石佳楠 钱舒琪 陈丽 《塑料》 CAS CSCD 北大核心 2024年第5期113-117,129,共6页
水凝胶微针是由具有三维网络结构的水凝胶材料制备得到,微针针体可以刺穿皮肤角质层,吸收皮肤间质液后溶胀转化为凝胶态,该性质使其在药物经皮促渗及对皮肤内生物标志物的提取识别领域具有重要作用。水凝胶微针能增大药物的经皮渗透性,... 水凝胶微针是由具有三维网络结构的水凝胶材料制备得到,微针针体可以刺穿皮肤角质层,吸收皮肤间质液后溶胀转化为凝胶态,该性质使其在药物经皮促渗及对皮肤内生物标志物的提取识别领域具有重要作用。水凝胶微针能增大药物的经皮渗透性,使用方便,由于针尖仅有微米级长度,使用时能达到无痛/微痛的目的,使用结束后,皮肤内无基质残留,还能通过改变水凝胶交联度调节释药速率。因此,总结了近年来水凝胶微针相关的国内外代表文献,介绍在制备工艺、性能评价方法及其应用的研究进展。 展开更多
关键词 水凝胶微针 制备工艺 性能评价 高分子材料 应用
下载PDF
高效柔性钙钛矿太阳电池研究
15
作者 白建明 于越 +1 位作者 李治学 彭飞 《太阳能学报》 EI CAS CSCD 北大核心 2024年第4期116-121,共6页
对柔性钙钛矿太阳电池(FPSCs)成膜工艺进行研究,针对在柔性基底上沉积薄膜不均匀、较多缺陷、内部应力等问题,分析其形成原因和影响因素。选择PET/ITO作为柔性基底,SnO2作为电子传输层,加入KCl进行调控,KCl的加入可增加电子传输层与柔... 对柔性钙钛矿太阳电池(FPSCs)成膜工艺进行研究,针对在柔性基底上沉积薄膜不均匀、较多缺陷、内部应力等问题,分析其形成原因和影响因素。选择PET/ITO作为柔性基底,SnO2作为电子传输层,加入KCl进行调控,KCl的加入可增加电子传输层与柔性导电基底的亲和性,从而获得致密且缺陷较少的膜层。通过优选钙钛矿前驱体各组分配比,加入MACl作为添加剂调控结晶过程,并在钙钛矿表面设计PEAI钝化层钝化界面,获得高质量的钙钛矿结晶和致密表面,并使电池的柔韧性能得到提升。在适宜的环境下,制备认证效率达到23.14%的柔性钙钛矿太阳电池,其在弯折10000次后仍能保持80.48%的初始光电转换效率。 展开更多
关键词 钙钛矿太阳电池 柔性 成膜工艺 制备环境
下载PDF
基于2020年版《中华人民共和国药典》含黄精成方制剂分析
16
作者 赵秋华 张忠伟 +1 位作者 薛强 盘家萍 《亚太传统医药》 2024年第12期203-208,共6页
目的:分析2020年版《中华人民共和国药典》(以下简称《中国药典》)中含黄精成方制剂的收载情况,为其综合开发研究提供参考依据。方法:查阅2020年版《中国药典》一部中含黄精的成方制剂,对含黄精成方制剂的名称、处方组成、黄精炮制品选... 目的:分析2020年版《中华人民共和国药典》(以下简称《中国药典》)中含黄精成方制剂的收载情况,为其综合开发研究提供参考依据。方法:查阅2020年版《中国药典》一部中含黄精的成方制剂,对含黄精成方制剂的名称、处方组成、黄精炮制品选材、常用配伍药、剂型、功效等情况进行数据统计,并归类分析。结果:2020年版《中国药典》一部收载的含黄精的成方制剂有31个(通过若干药味组成、功能主治一致,仅剂型存在差异的制剂则合并为某方,合并后统计含黄精处方为21个),处方组成的药味数少则有4味,多则有22味;选材主要为黄精(57.14%);常用配伍药有黄芪(炙黄芪)(57.14%)、地黄(熟地黄)(52.38%)、枸杞(42.86%)等;剂型有片剂(35.48%)、胶囊剂(25.81%)、颗粒剂(22.58%)等;功效以滋补肝肾(85.71%)和补气(57.14%)为主。结论:2020年版《中国药典》一部收载的含黄精的成方制剂较少,黄精选材名称不够规范,剂型分布少,制法简单,无黄精有效成分作为含量检测指标,应加强黄精在复方制剂中的综合开发研究。 展开更多
关键词 黄精 《中国药典》 成方制剂 剂型
下载PDF
Are the release characteristics of Erzhi pills in line with traditional Chinese medicine theory?A quantitative study
17
作者 Jie-yu Zuo Chulhun Park +1 位作者 Michael Doschak Raimar Lobenberg 《Journal of Integrative Medicine》 SCIE CAS CSCD 2021年第1期50-55,共6页
Objective:Traditional Chinese medicine(TCM)has been widely used throughout China to prevent and cure diseases for thousands of years,and now it is a part of the integrative medicine field that is available in Western ... Objective:Traditional Chinese medicine(TCM)has been widely used throughout China to prevent and cure diseases for thousands of years,and now it is a part of the integrative medicine field that is available in Western societies.To ensure the safety and quality of the herbal medicines that are a major part of the TCM tradition,they must be held to modern pharmaceutical standards.Erzhi pill(EZP)is a Chinese Pharmacopeia-listed herbal preparation that is used in the long-term clinical management of postmenopausal symptoms,osteoporosis and menstrual disorders.Until now,whether the drug release mechanism of EZP is in line with its intended TCM usage has not been studied.Methods:The release of specnuezhenide from three EZPs(self-made,Leiyunshang and Renhe)in simulated gastric fluid(SGF),acetate buffer(p H 4.5 buffer)and simulated intestinal fluid(SIF)was investigated in a dissolution test.The water uptake capacity and erosion extent of the three EZPs were investigated using swelling and erosion studies.The drug release mechanism was further assessed through statistical model fitting,using DDSolver software.Results:The release of specnuezhenide from all three EZPs in SGF was less than 50%within a 4 h period.However,over 70%of the specnuezhenide was released from each EZP in both p H 4.5 buffer and SIF in the same time.Analysis of the swelling and erosion behaviors and the drug release mechanism of the three EZPs confirmed that the release rate from EZP followed a sustained release profile,which was an interactive combination of swelling and erosion.Conclusion:This study showed that the release pattern from the pills was in line with the intended TCM use of EZP.TCM had not only theoretically considered sustained release from the pills,but also formulated them to achieve this release pattern.When establishing quality control standards for pills,the theoretical TCM usage and the actual release patterns need to be considered. 展开更多
关键词 Traditional Chinese medicine Dosage form Herbal preparation DISSOLUTION Drug release mechanism Erzhi pill
原文传递
Influences of preparation techniques on glass-forming ability of Fe-P-B-Si-C amorphous alloys
18
作者 Ji-jun Zhang Ya-qiang Dong +3 位作者 Lu-yang Bie Qiang Li Jia-wei Li Xin-min Wang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2018年第6期674-679,共6页
It has been widely accepted that the ultrafast cooling rate is required for the glass formation of amorphous alloys. Here, the larger glass-forming ability (GFA) of Fe76P5(B0.5Si0.3C0.2)19 amorphous alloy was achi... It has been widely accepted that the ultrafast cooling rate is required for the glass formation of amorphous alloys. Here, the larger glass-forming ability (GFA) of Fe76P5(B0.5Si0.3C0.2)19 amorphous alloy was achieved by water quenching at lower cooling rate under argon atmosphere. Cylindrical rods with diameters of 1-2 mm were prepared by water quenching without flux treatment, Cu-mold injection casting, and Cu-mold suction casting, respectively. The influences of the preparation techniques with different cooling rates on GFA, thermal property, and nucleation/growth behavior were examined. The critical diameter of the Fe76P5(B0.5Si0.3C0.2)19 amorphous alloys is 1.7 mm for water quenching while smaller than 1.0 mm for injection casting. Microstructure analysis indicates that the crystallization and solidification processes are quite different between the water-quenched and the injection-cast rods. These findings could deepen fun-damental understanding on the relationship between the cooling rate, techniques, and GFA of Fe-based amorphous alloys. 展开更多
关键词 Fe-based amorphous alloy Preparation technique Glass-forming ability Crystallization behavior
原文传递
喷射打印成型用陶瓷墨水制备方法 被引量:25
19
作者 郭瑞松 齐海涛 +3 位作者 郭多力 吕晓娟 陈玉如 杨正方 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2001年第6期1049-1054,共6页
简介了喷射打印成型技术的概念,论述了制备陶瓷墨水的几种可行方法;就有关报道及天津大学在该领域开展的工作做了总结.通过分析,作者认为,分散法虽然工艺简单,但分散性和稳定性不够理想.溶胶法制备的陶瓷墨水颗粒细、分散性较好... 简介了喷射打印成型技术的概念,论述了制备陶瓷墨水的几种可行方法;就有关报道及天津大学在该领域开展的工作做了总结.通过分析,作者认为,分散法虽然工艺简单,但分散性和稳定性不够理想.溶胶法制备的陶瓷墨水颗粒细、分散性较好,但稳定性有待提高.反相微乳液法可获得高度分散、高度稳定的陶瓷墨水,陶瓷颗粒的粒度可以达到纳米级,但如何提高其固含量是一个亟待解决的技术难题. 展开更多
关键词 陶瓷墨水 分散法 溶胶法 反相微乳液法 制备 喷射打印成型 陶瓷成型工艺
下载PDF
半固态A356铝合金流变挤压铸造工艺 被引量:15
20
作者 刘艳华 熊洪淼 +2 位作者 郭洪民 王家宣 杨湘杰 《特种铸造及有色合金》 CAS CSCD 北大核心 2008年第2期122-124,共3页
将剪切低温浇注式半固态流变制浆方法(LSPSF)与直接挤压铸造工艺相衔接,开发了一种浆料制备与零件成形相分离的流变成形系统;在YB32-300型四柱万能液压机上成功进行了铝合金弹壳体(深筒薄壁件)流变挤压铸造试验,并研究了成形件不同部位... 将剪切低温浇注式半固态流变制浆方法(LSPSF)与直接挤压铸造工艺相衔接,开发了一种浆料制备与零件成形相分离的流变成形系统;在YB32-300型四柱万能液压机上成功进行了铝合金弹壳体(深筒薄壁件)流变挤压铸造试验,并研究了成形件不同部位的显微组织。结果表明,新开发流变成形系统可以解决定量浇注与浆料输送问题,获得表面品质优异的成形件,且工艺流程简单,浆料成形性能良好。由于所受压力分布不均匀,成形件内部不同部位的显微组织存在差距。在零件的横断面,中部固相近球形颗粒数目增多,靠近零件内表面边缘的固相近球形颗粒数目减少,树枝晶数量明显增多。而底部显微组织与半固态浆料成形前的显微组织基本一样。 展开更多
关键词 流变成形 浆料制备 挤压铸造 微观组织
下载PDF
上一页 1 2 20 下一页 到第
使用帮助 返回顶部