对3种包埋料铸出的钛铸件表面反应层的研究

目的:检测不同体系包埋料铸出的钛铸件表面反应层组成、显微结构及硬度变化。方法:分别用3种不同体系的包埋料包埋铸造钛铸件,肉眼观察铸件表面颜色;用电子探针对铸件表面反应层组成、显微结构进行分析;用显微硬度仪测试铸件表面硬度值。结果:氧化硅系、氧化铝系、氧化镁系包埋料铸出的钛铸件表面颜色分别是黑色、银灰色、橙黄色;表面反应层厚度分别是80μm、50μm、14μm;表面硬度结果显示:氧化硅系、氧化铝系、氧化镁系铸件分别在距表面120μm、80μm、40μm内硬度值明显减少,超出此范围变化较小;3种铸件表面硬度值在距表面120μm后趋于一致。结论:氧化硅系包埋料铸出的钛铸件表面反应层厚度最厚,反应最多;氧化镁系包埋料铸出的钛铸件表面反应层厚度最薄,反应最少;氧化铝系包埋料处入它们两者之间。从反应层的角度来看,氧化镁系包埋料是这3种包埋料中最理想的铸钛包埋料。     

不同包埋材料对Ti-6Al-7Nb合金铸流率的影响

目的:比较3种不同包埋材料对医用Ti-6Al-7Nb合金铸流率的影响.方法:采用网状试样法,以纯钛为对照,分别对3种不同体系包埋材料(氧化镁系、磷酸盐系、氧化锆系)铸出的Ti-6Al-7Nb合金试件的铸流率进行评价.结果:各组试件铸流率均达到90%以上,3种包埋料包埋的铸件铸流率无明显差异(P＞0.05),纯钛组和Ti-6Al-7Nb组间也无显著性差异(P＞43.05).结论:Ti-6Al-7Nb合金与纯钛一样具有较高的铸流率,且受3种包埋料的影响均较小.     

不同包埋材料对Ti-6Al-7Nb合金铸造全冠适合性的影响

目的：研究不同包埋材料对Ti-6Al—7Nb合金铸造全冠适合性的影响，筛选出适合于临床应用的包埋材料。方法：采用氧化镁系、磷酸盐系、氧化锆系包埋材料包埋模拟后牙牙冠的帽状蜡型，用Ti-6Al—7Nb合金铸造，铸件组织面经喷砂后就位于各自的不锈钢代型上，在金相显微镜下分别测试铸件的边缘适合性和组织面密合度，统计分析各组均值之间的差异。结果：3种包埋料各点间隙均小于120μm，氧化镁系组和磷酸盐系组包埋材料铸出试件的各测量点间隙没有显著性差异（P〉0．05），氧化镁系组和磷酸盐系组边缘间隙值明显小于氧化锆系组边缘间隙值（P〈0．05）。结论：3种包埋料均适合于Ti-6Al—7Nb合金的包埋铸造，但氧化镁系组包埋料精度更高。     

不同包埋方法钛铸件的成孔性与力学性能

目的 本实验目的在于研究不同包埋方法铸造的纯钛铸件的成孔性是否影响其力学性能。方法 采用三种不同的铸模包埋方法，离心铸造商业纯钛，经Ｘ探伤，计算机图象分析，金相照片，显微硬度及力学测试。结果 结果表明①一次包埋法铸件气孔明显少于两次包埋法；②铸件内较大气孔严重影响力学性能；结论 包埋料和铸型形状与铸件气孔有密切关系。建议铸钛义齿，常规作Ｘ探伤检查。     

不同包埋材料对铸造纯钛铸件表面硬化层的影响

目的 研究两种不同包埋材料对铸件表面硬化层的影响.方法 用铸造蜡片制作尺寸为20 mm×20 mm×1.5 mm的片状试件共6片,分为2组,实验组采用新型铸钛包埋材料包埋,对照组采用Rematitan:Plus专用铸钛包埋料包埋铸造.铸件处理后用显微硬度仪测试表面硬度,负重200 g持续5 s,测量维氏显微硬度值,比较...     

包埋料和铸道参数对Ti-24Nb-4Zr-7.9Sn合金铸流率的影响

目的:优选适合Ti-24Nb-4Zr-7.9Sn合金铸造的包埋料、铸道直径和长度, 以便提高该合金的铸流率.方法:采用网状试样法,计算 Ti-24Nb-4Zr-7.9Sn合金在3 种包埋料、3 种铸道直径和长度条件下的铸流率,做析因设计的统计学分析.结果:包埋料、铸道直径和长度对Ti-24Nb-4Zr-7.9Sn合金的铸流率均有显著影响(P<0.05),但不认为包埋料、铸道直径和长度两两之间及三者相互之间存在交互作用(P>0.05).结论:使用氧化镁系铸钛专用包埋料,选择直径5 mm、长度5 mm的铸道包埋铸造,可取得铸流率高达(94.90±4.67)%.     

不同铸造条件对纯钛铸件表面粗糙度的影响

目的：探讨包埋料及铸造温度等铸造条件对纯钛铸件表面粗糙度的影响。方法：铸型用氧化锆包埋料内包埋后再用磷酸盐包埋料包埋或只用磷酸盐包埋料包埋片状蜡型，用ＬＺ型牙科铸钛机分别在室温、３００℃和９００℃条件下铸造Ｇｒ２型纯钛，并分别用磷酸盐和硅酸乙酯包埋料常规包埋铸造钴铬（Ｃｏ－Ｃｒ）合金作比较，使用表面粗糙度仪对铸件的表面粗糙度（Ｒａ）进行测定。结果：铸造纯钛时，使用氧化锆内包埋且铸型温度在３００℃或室温铸造的纯钛铸件Ｒａ值无显著差别（Ｐ＞０．０５），且低于其它条件下铸造的纯钛铸件和常规铸造的（Ｃｏ－Ｃｒ）合金的表面粗糙度（Ｐ＜０．０１）。结论：使用氧化锆内包埋且铸型温度在３００℃以下铸造Ｇｒ２型纯钛，其铸件表面粗糙度较小。     

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钛铸件质量与包埋材料关系已成为口腔材料学研究热点之一。进口铸钛包埋材料虽好但价格昂贵。本研究使用我科自配ZrP99铸钛包埋材料包埋铸造钛件,通过检测不同铸模温度时钛铸件的金属表面性状、内部气孔含量和     

新型牙科铸钛包埋材料铸造纯钛铸件的粗糙度研究

目的 探讨自行研发并已获得国家发明专利的新型牙科铸钛包埋材料和商品铸钛包埋材料铸造纯钛铸件的表面粗糙度差异,以期为临床应用提供依据.方法 制作20 mm×20 mm×0.5 mm的蜡型6片,分为A、B两组,每组3片,分别用新型牙科铸钛包埋材料和商品铸钛包埋材料( Rematitan Plus)包埋铸造纯钛铸件.表面粗糙度检查仪测试铸件表面粗糙度,每个铸件测试3个部位,表面描记长度为5.6 mm,比较两组铸件表面粗糙度Ra值的差异.结果 A组铸件表面粗糙度Ra值为(1.72±0.08) μm,小于B组[(1.91 ±0.15) μm],差异有统计学意义(P＜0.05).结论 新型牙科铸钛包埋材料所铸钝钛铸件的表面粗糙度比目前临床常用的商品铸钛包埋材料所铸钝钛铸件表面粗糙度小,可满足临床应用要求.     

自制钛包埋方法和铸模冷却方式的研究

目的 综合考察不同包埋方法和铸模冷却方式对自制铸钛包埋材料纯钛铸件多种性能的影响。方法 研究自制铸钛包埋材料的一次包埋法和二次包埋法对纯钛铸件的流铸率和全冠铸造精度的影响,以及铸造后铸圈自然冷却方式和骤冷方式对纯钛铸件的反应层、力学性能及全冠铸造精度的影响。结果 一次包埋组和二次包埋组钛铸件的流铸率均为100％,但一次包埋组铸钛全冠适合性较好,达到临床要求。自然冷却组钛铸件表面的反应层厚度（115 μm）较骤冷组（100 μm）厚,铸件强度较骤冷组高（P<0.05）,而两组的延伸率无统计学差异：自然冷却组全冠适合性较好,达到临床要求。结论 自制铸钛包埋材料试料宜采用一次包埋法和铸模自然冷却方式。     

The effects of different types of investments on the alpha-case layer of titanium castings

STATEMENT OF PROBLEM: Different types of investments affect the formation of the alpha-case (alpha-case) layer on titanium castings. This alpha-case layer may possibly alter the mechanical properties of cast titanium, which may influence the fabrication of removable and fixed prostheses. The formation mechanism for the alpha-case layer is not clear. PURPOSE: The aim of this study was to evaluate the effect of 3 types of investments on the microstructure, composition, and microhardness of the alpha-case layer on titanium castings. MATERIAL AND METHODS: Fifteen wax columns with a diameter of 5 mm and a length of 40 mm were divided into 3 groups of 5 patterns each. Patterns were invested using 3 types of investment materials, respectively, and were cast in pure titanium. The 3 types of materials tested were SiO(2)-, Al(2)O(3)-, and MgO-based investments. All specimens were sectioned and prepared for metallographic observation. The microstructure and composition of the surface reaction layer of titanium castings were investigated by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The surface microhardness (VHN) for all specimens was measured using a hardness testing machine, and a mean value for each group was calculated. RESULTS: The alpha-case layer on titanium castings invested with SiO(2)-, Al(2)O(3)-, and MgO-based investments consisted of 3 layers-namely, the oxide layer, alloy layer, and hardening layer. In this study, the oxide layer and alloy layer were called the reaction layer. The thickness of the reaction layer for titanium castings using SiO(2)-, Al(2)O(3)-, and MgO-based investments was approximately 80 microm, 50 microm, and 14 microm, respectively. The surface microhardness of titanium castings made with SiO(2)-based investments was the highest, and that with MgO-based investments was the lowest. CONCLUSIONS: The type of investment affects the microstructure and microhardness of the alpha-case layer of titanium castings. Based on the thickness of the surface reaction layer and the surface microhardness of titanium castings, MgO-based investment materials may be the best choice for casting these materials.     

Layered structure of cast titanium surface

The present study concerns the surface layered structure of the cast Ti. A commercial Ti was cast into a mold which was made of a phosphate-bonded Al2O3/SiO2 investment. Elemental analyses of the interfacial zone of the casting were made under an electron probe micro-analyzer. The interfacial zone was composed of four layers: the outermost reaction or casting burn layer, the second layer of an O-and Al-stabilized alpha case, the third layer in which Si, P, O, and C were inhomogeneously concentrated, and the fourth layer which consisted of acicular or plate-like crystals. It was observed that the larger the cast volume and the higher the mold temperature, the thicker became each layer and the coarser became the acicular grains. Probably, the layered structure was formed through decomposition of reducible species in the burnout investment and diffusion of the resulting elements into the casting.     

Development of Al2O3 fiber-reinforced Al2O3-based ceramics

The purpose of this study was to use a tape casting technique to develop an Al2O3 fiber-reinforced Al2O3-based ceramic material (Al2O3-fiber/Al2O3 composite) into a new type of dental ceramic. The Al2O3-based ceramic used a matrix consisting of 60 wt% Al2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of Al2O3-fiber/Al2O3 composite (in which uniaxially aligned Al2O3 fibers were infiltrated with the Al2O3-based matrix) were fabricated continuously using tape casting technique with a doctor blade system. Multilayer preforms of Al2O3-fiber/Al2O3 composite sheets were then sintered at a maximum temperature of 1000 degrees C under an atmospheric pressure in a furnace. The results showed that the shrinkage and bending properties of Al2O3-fiber/Al2O3 composite exceeded those of unreinforced Al2O3--hence demonstrating the positive effects of fiber reinforcement. In conclusion, the tape casting technique has been utilized to successfully develop a new type of dental ceramic material.     

ZrP99铸钛包埋材料的铸模温度对铸造精度的影响

目的：研究ZrP99铸钛包埋材料的铸模温度对铸造精度的影响。方法：利用代型模具，制作30个超硬石膏全冠预备体代型．并制作相应的全冠蜡型，随机分为5组，每组6个样本，其中4组为实验组，采用ZrP99铸钛包埋材料进行包埋，分别在铸模温度为600℃、450℃、300℃、150℃条件下进行铸造；另外一组为对照组，采用Titavest—CB包埋材料进行包埋．在铸模温度为600℃条件下进行铸造。利用显微图像分析技术．在实体显微镜下分别测量蜡型及相应的铸件边缘与代型肩台之间在标志点处的间隙，两者差值即代表铸造精度。采用t检验及单因素方差分析进行统计学处理。结果：Titavest—CB包埋材料组的铸造精度显著优于在不同铸模温度下ZrP99包埋材料组：当ZrP99包埋材料的铸模温度低于450℃时，随着温度升高，铸造精度显著提高。结论：ZrP99铸钛包埋材料的铸模温度必须高于300℃．才有可能满足临床精度要求。     

不同包埋料对铸钛表面反应层结构的影响

目的比较不同包埋材料对铸钛表面反应层结构的影响。方法制作统一规格的有机玻璃板试样,试验组分别用SYMBION TM,TITAN SUPER MILD A,Ti 21 Investment包埋料内包埋,普通磷酸盐包埋料外包埋,对照组用Multi-Vest包埋料包埋,各铸件沿纵轴截断,采用观测金相组织和显微硬度比较各铸件表面反应层。结果各试验组铸件表面污染层厚度均<80μm,与铸钛表面显微硬度的变化相一致。结论本研究选用的3种钛包埋料,应用二次包埋法包埋,可满足临床需要。     

Novel method for titanium crown casting using a combination of wax patterns fabricated by a CAD/CAM system and a non-expanded investment.

OBJECTIVES: For titanium casting, most commercial investments for titanium recommend casting at a low mold temperature to reduce oxidation. However, the thermal expansion values of the molds at low casting temperatures may be insufficient. The purpose of the current study was to investigate the possibility of obtaining accurate titanium crown casts using wax pattern fabricated by a CAD/CAM system with a non-expanded mold. METHODS: Three types of experimental magnesia-based investments (A, B and C) were made and their properties were evaluated for dental use. Two kinds of wax patterns for full-coverage coping crowns (S-0: cement space of 0 microm; S-20: cement space of 20 microm) were fabricated using a commercial CAD/CAM system. A traditional method (TM) using inlay wax was performed for comparison. The investment for titanium casting was decided from the fundamental data of experimental investments. Titanium crowns were replaced on the stone die and the thickness of the cement layer was evaluated. RESULTS: There were no significant differences for the setting time and setting expansion among the experimental investments, but the aluminous cement content played a role in hardening and contracting the mold. The fit of the titanium crowns differed significantly between the TM and the CAD/CAM system. The ranges of thickness obtained from the TM, S-0 and S-20 were 20.78-357.88 microm, 25.12-107.46 microm and 17.84-58.92 microm, respectively. SIGNIFICANCE: High quality titanium crown casting was obtained using a combination of wax patterns fabricated by a CAD/CAM system and a non-expanded MgO-based investment.     

烧烤及铸造温度对纯钛铸件表面结构的影响

以磷酸盐包埋料为主,配制不同粒度的耐火材料和不同比例的结合剂作为纯钛铸造的包埋料。并对其不同烧烤温度和铸造温度下铸造成形的铸件进行X线内部检查与表面光洁度、表面硬度及金相显微观察等。结果表明降低耐火材料的粒度和结合剂中的磷氨含量,用高温加热、低温铸造的方法可以减少纯钛表面层与包埋料的反应。     

Casting pure titanium into commercial phosphate-bonded SiO2 investment molds

Pure titanium was cast into five different phosphate-bonded SiO2 investment mold materials (at 350 degrees C) with an argon-arc melting and pressure casting machine. The mesh castability, the fit of the MOD inlay castings, and the Knoop hardness and the micro-structure in cross-sections of castings were examined. The setting and thermal expansion, the compressive strength, and the X-ray diffraction analysis of the investments were also measured. The castability, the fit, and the thickness of the reacted layer differed in degree among these investments, in spite of the same phosphate-bonded SiO2-type investment. A significant correlation was obtained between the thermal expansion (at 350 degrees C) and the casting accuracy.     

纯钛冠桥铸造包埋料对铸件反应层的影响

目的探讨自行研制包埋材料（FUS-invest）中各组分对纯钛铸件反应层的影响。方法使用FUS-invest包埋并铸造10 mm×10 mm×1 mm的纯钛试样3片,观察反应层的金相,对反应层进行X射线衍射（XRD）及扫描电镜能谱分析（EDS）,测量显微维氏硬度。结果反应层的金相主要为粗大的片状α晶内结构,显微维氏硬度值在距表面105 μm后较为恒定,范围为243～314 MPa。XRD显示反应层中除了钛基体外,主要由ZrO2、SiO2、Mg2TiO4及TiO2组成。EDS检测到的元素除了钛元素外,主要为Al、Si、Zr和Cl。结论使用FUS-invest包埋材料铸造的纯钛铸件产生的反应层较薄,金相结构没有显著改变,适合作为纯钛铸造的专用包埋材料。     

新型铸钛包埋材料不同铸模温度对纯钛铸流率影响的研究

目的探讨新型铸钛包埋材料在不同铸模温度下对纯钛铸流率的影响。方法采用Hinman的测试方法,制作20mm×20mm×0．85mm、具有10×10格的网状蜡型,分别在铸模温度为400℃、600℃、800℃进行铸造。铸造完成后,统计钛铸件的格数和边数,分别计算蜡型和铸件格数与边数的百分比。同时在扫描电镜下观察新型铸钛包埋材料模型烧结后的显微结构．进一步判断影响铸流率的原因。结果纯钛在400℃、600℃、800℃铸模温度下的铸流率均为100％。扫描电镜下观察．新型铸钛包埋材料间有大量细小的孔隙．且相互交错贯通。表明自制包埋料透气性能良好。结论新型铸钛包埋材料的铸流率测试结果良好．说明在600℃～800℃的温度范围内的铸流率均足以满足临床的应用要求。