包埋料和热处理对自研贵金属合金铸造适合性的影响

目的　比较不同包埋料和热处理方法对牙科铸造贵金属合金BS 1金合金铸件铸造适合性的影响。方法　采用 2种包埋料 (F 1和Z 1包埋料 )包埋模拟后牙冠的帽状代型蜡型 ,用BS 1金合金铸造 ,铸件经过不同的热处理 (软化热处理 ,硬化热处理和恒温时效硬化热处理 )后试合于各自的石膏代型 ,在体视显微镜和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 ,求各自的平均值 ,统计分析各组之间的统计学差异性。结果　F 1包埋料组的边缘差异明显小于Z 1包埋料组 (P <0 0 5 )。热处理对金合金铸件的铸造适合性无显著性影响。结论　BS 1金合金用F 1包埋料包埋铸造的铸件其铸造适合性优于Z 1包埋料组。热处理对其铸造适合性无显著性影响     

金属元素铍对烤瓷合金铸流率影响的实验研究

目的:比较两种烤瓷合金的铸流率,了解金属元素铍对合金铸流率的影响。方法:采用网状试件,通过直接法计算两种烤瓷合金的铸流率(Cv)值,比较两种包埋料(F-1和F-2包埋料)对两种合金铸流率的影响。结果:含铍烤瓷合金和不含铍烤瓷合金的铸流率均在95%以上,两种烤瓷合金的铸流率无显著性差异(P>0.05);两种包埋料对两种烤瓷合金的铸流率的影响在统计学上均无显著性差异(P>0.05)。 结论:金属元素铍对烤瓷合金的铸流率无重要影响;两种包埋料对两种烤瓷合金的铸流率无显著影响。     

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。     

高铌钛合金铸流率的探讨

目的以钛铌锆锡（Ti—Nb—Zr—Sn）合金为研究对象,通过对其铸流率的研究,探讨高铌钛合金用于牙科铸造加工的可行性．并为牙科应用提供合理的铸造参数。方法采用网状试样法。检测钛铌锆锡合金在3种铸模温度（室温、300℃、600℃）下的铸流率,并以纯钛（Ti）、钛铝钒（Ti－6A1－4V）合金做对照,结果做统计学分析。结果在室温及300℃铸造时钛铌锆锡合金铸流率明显低于纯钛及钛铝钒合金;在600℃铸造时三种合金铸流率没有明显差别。该合金室温及300℃组铸流率明显低于600℃组。结论高铌钛合金在室温铸造时铸流率不佳,钛铌锆锡合金在铸模温度高于600℃以上铸造时可以获得完整铸件。     

不同铸造合金对铸造冠边缘适合性影响的实验研究

目的观察Dentaurum包埋材料与3种牙科合金匹配对铸造冠边缘适合性的影响。方法制作模拟后牙全冠外形的标准帽状试件及圆管,于试件上制作30个熔模,随机分为3组,每组按照Dentaurum包埋材料的使用说明进行有圈包埋,分别采用3种合金进行铸造。铸造冠在原标准帽状试件上试合,在扫描电镜下测量铸件的边缘浮出量。结果第1组铸造冠与其余2组的边缘浮出量差异有显著性(P<0.05)。其余2组间的边缘浮出量差异无显著性(P>0.05)。结论Dentaurum包埋材料与Dentaurum NiCrMo合金有良好的匹配性,与其余2种合金匹配其边缘浮出量也在临床允许范围内。     

牙科合金的铸造性能研究进展

牙科精密铸造工艺多用熔模铸造又称失蜡铸造法 ,其基本过程是先用蜡或塑料等制成蜡型 ,蜡型表面涂敷包埋料制作铸型 ,然后熔化合金铸入铸型腔内 ,形成铸件。在这一系列过程中 ,每一个步骤都对最终的铸件完整性产生影响 ,而铸件完整性对牙科合金铸造成功与否起着关键的作用。研究牙科合金的铸造性能即研究牙科合金能够完全铸入铸型腔的能力 ,也即实际铸入铸型腔内的合金占应该铸入铸型腔内合金量的百分比 (一般用Ｃｖ即铸流率表示 )。虽然牙科合金的铸造历史很长 ,但对其铸造性能的研究方法还没有达到广泛的一致 ,总的来说研究牙科合金铸造性…     

不同包埋方法对钯银合金铸件边缘适合性的影响

目的:观察有圈包埋及无圈包埋方法对铸造钯银合金边缘适合性的影响。为临床制作钯银合金冠选择合适的包埋方法提供依据。方法:在同一石膏模型上制作40个钯银合金基底冠蜡型,分别进行有圈包埋和无圈包埋。铸件黏固于代型后从中线切成相等两份,检测每组基底冠边缘和轴壁相对应的黏固剂厚度, 研究相比边缘适合性。用SPSS统计学软件对本实验数据进行处理。结果:无圈包埋组试件的边缘适合性与有圈包埋组相比有显著性差异(P<0.05)。结论:钯银合金铸造采用无圈包埋时的适合性优于有圈包埋。铸造钯银合金采用无圈包埋,能够有较好的边缘适合性,为患者提供更完美的修复效果。     

铸模温度对Ti-75合金铸流率影响的研究

通过对Ｔｉ－７５合金铸流率的研究,为Ｔｉ－７５合金临床应用提供合理的铸造参数。方法：采用网状试样法,对Ｔｉ－７５合金、纯钛及Ｔｉ－６Ａｌ－４Ｖ合金在３种铸模温度下的铸流率进行评价。结果：Ｔｉ－７５合金在室温铸造时其铸流率明显低于纯钛及Ｔｉ－６Ａｌ－４Ｖ合金,并用室温用Ｔｉ－７５合金在室温铸造时其铸流率明显低于３００℃及６００℃组。结论为保证临床义齿铸造的完整性,Ｔｉ－７５合金铸造时铸模温度应在３０     

Evaluation of an improved centrifugal casting machine

A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines.     

Mesh monitor casting of Ni-Cr alloys: element effects

A mesh monitor has previously been used for quantitative evaluation of the casting of dental alloys. A castability value, Cv was defined. For curve-fitting, a transformed castability value, Cv,t, was used. A series of alloys was selected so that effects of major elements on Cv, t and, hence, on Cv could be determined. Compositions were chosen so that correlated effects would be avoided. Assuming a linear dependence on the concentrations of individual elements, one may use the following equation to describe Cv,t: (Formula: see text) where each term employs an elemental concentration in weight percent, (Ei), and a coefficient, Ki, for the ith term. Because Ei's are constant for each alloy, Ki = fi (TA, TM) = gi (TC, TM). The temperature-dependent coefficients, Ki, were determined for seven elements and for the (Ni/(Cr) ratio. It was also found that Si and Be produce a synergistic effect. The results help our understanding of the casting behavior of Ni-Cr dental alloys; this approach may be useful in the design of dental alloys.     

Comparison of two tests to determine the castability of dental alloys

This study compared castability values in the Whitlock test with those obtained from a new castability monitor based on a dental restoration. Five metal ceramic casting alloys were induction cast with both a carbon-containing and a noncarbon phosphate-bonded casting investment to assess the reliability of the Whitlock mesh test in predicting alloy castability. Alloy performance in the Whitlock test did not parallel that of the replica coping test for all alloy-investment pairs, as would be anticipated for a reliable monitor of castability. In addition, the variability of the Whitlock castability values for some alloys was sufficient to question the test's usefulness in refining the casting process with a specific alloy.     

Dental casting of titanium and Ni-Ti alloys by a new casting machine

The purpose of this study was to develop a new casting machine for titanium and Ni-Ti alloys. Properties of cast pure titanium and Ni-Ti alloys were studied by means of the tensile and casting tests. As gas in the mold was removed by the mold being heated under a high vacuum, the reaction between the molten metal and the mold decreased. The new control system and the two types of crucibles developed proved very useful for prevention of internal macro-defects in castings and for improvement of castability. Mechanical properties and castability of pure titanium were improved. Ni-Ti alloys could be cast without loss of their shape-memory effect or super-elasticity characteristics. The new casting machine is thought to be promising for the casting of titanium and Ni-Ti alloys. Furthermore, we can cast these alloys using conventional techniques and investments.     

A technique for characterizing casting behavior of dental alloys

A technique for characterizing casting behavior of dental alloys has been developed and tested. The method employs easily reproducible specimen patterns and uses equipment and procedures generally available in dental prosthetic laboratories. A castability value is arrived at by counting complete segments of a cast alloy grid. Test results indicate that the castability evaluation procedure described can be a valuable aid in the laboratory for both selecting and using dental materials for producing cast restorations. The test method would also appear useful for the evaluation of products and techniques during research and development. An absolute minimum for the castability value determined relative to clinical and laboratory efficacy has yet to be established.     

On deffect of cobalt-chromium-nickel alloy for dental castings (author's transl)]

We studied about castability and microporosity of cobalt-chromium-nickel alloy for dental casting in various methods of fusion and casting. The combinations of fusion and casting were induction fusion and centrifugal casting, arc discharge fusion and argon gas pressure casting and oxy-acetylene flame fusion and centrifugal casting. The following results were obtained. 1. The amount of microposity was smaller, when only mold temperature was low, and as mold temperature and casting temperature were high, castability was better. 2. The arc discharge fusion and argon gas pressure casting was the best method about castability and microporosity in three methods. Second method was the induction fusion and centrifugal casting. 3. In the induction fusion and centrifugal casting, blowing arong gas of 1 l/min to molten metal to protect the metal from oxidization improved the castability the best, but amount of microporosity was large, so that it was needed to lower the mold temperature in this condition. 4. The oxyacetylene flame fusion and centrifugal casting was not suitable for the casting of Co-Cr alloy "Regalloy No. 3", for the alloy was made for the induction fusion casting.     

New high-palladium casting alloys: 1. Overview and initial studies.

High-palladium alloys for metal ceramic restorations, based on the Pd-Cu-Ga and Pd-Ga systems, were introduced to the dental profession during the past decade. These alloys have become increasingly popular because they are much less expensive than the gold-based alloys, and recently marketed high-palladium alloy compositions have excellent mechanical properties. A summary of the important melting and casting considerations for these somewhat technique-sensitive alloys is presented together with an overview of important dental materials science aspects and the results of a dental laboratory survey. A maxillary central incisor coping was chosen as the clinically appropriate specimen shape, and the gas-oxygen torch melting technique was found to produce castings with clinically acceptable levels of marginal sharpness and little evidence of microporosity. The etched as-cast high-palladium alloys exhibited fine-scale multiphase microstructures, and a noteworthy finding was that relative proportions of the microstructural constituents frequently varied for thin versus thick sections of the cast specimens.     

铸模温度对牙科用Ti-Zr合金铸流率影响的研究

目的：通过对Ti-Zr合金铸流率的研究,为Ti-Zr合金临床应用提供合理的铸造参数,方法：采用网状试样法, 测量Ti-Zr合金,纯钛及Ti-6Al-4V合金在3种铸模温度（室温,300度,600度）下的铸流率,结果：Ti-Zr合金在室温铸造时其铸流率明显低于纯钛及T-6A-4V合金,并且Ti-Zr合金的铸流率也明显低于300度及600度组,结论：为保证 临床义齿铸造的完整性,Ti-Zr合金铸造时模温度应在300度以上。