The Experts below are selected from a list of 4773 Experts worldwide ranked by ideXlab platform
Egbe Kelle - One of the best experts on this subject based on the ideXlab platform.
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Mold Filling and dimensional accuracy of titanium castings in a spinel based investment
Dental Materials, 2009Co-Authors: Jens Fische, Andreas Ebinge, Tobias T Hagi, Ogna Stawarczyk, Andreas Wenge, Egbe KelleAbstract:OBJECTIVES: Aim of the study was to analyze the Mold Filling capacity and the dimensional accuracy of a spinel-based investment for titanium castings. METHODS: Expansion of the investment in dependence of the preheating temperature was measured in a dilatometer. The degree of transformation of MgO and Al2O3 to spinel (MgAl2O4) was evaluated by means of X-ray powder diffraction. Mold Filling capacity was assessed by casting a grid and calculating the percentage of completed segments. Dimensional accuracy was analyzed by casting a hollow cylinder and measuring the difference between the inner diameter of the resin pattern and the resulting titanium casting. RESULTS: Spinel formation starts at 819 degrees C. Diffraction patterns prove the formation of spinel from MgO and Al2O3. The amount of spinel increases with increasing preheating temperature. The final expansion of the investment at the end of the preheating cycle at 450 degrees C shows a linear correlation to the maximum preheating temperature. The degree of Mold Filling is reciprocal to the preheating temperature. The dimensional accuracy shows a linear correlation to the amount of spinel. Best dimensional accuracy was obtained at about 900 degrees C. After a preheating temperature of 884 degrees C, as recommended by the manufacturer, the cast specimens showed a slightly lower inner diameter as compared to the resin patterns. SIGNIFICANCE: The results suggest that with the spinel investment analyzed an excellent accuracy of titanium castings may be obtained.
Hu Zhang - One of the best experts on this subject based on the ideXlab platform.
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Pressure-driven Mold Filling model of aluminum alloy melt/semi-solid slurry based on rheological behavior
Journal of Materials Science & Technology, 2020Co-Authors: Ma Zhen, Huarui Zhang, Wei Song, Lina Jia, Hu ZhangAbstract:Abstract The pressure-driven Mold Filling ability of aluminum alloy melt/semi-solid slurry is of great significance in pressure casting processes, and the rheological behavior of the alloy has a crucial effect on the Mold Filling ability according to fluid dynamics. In this work, a pressure-driven Mold Filling model is first proposed based on the rheological behavior of the alloys. A356 alloy is employed as an example to clarify the rheological behavior of aluminum alloys, which obeys the power law model and is affected by temperature. The rheological behavior of the alloy in semi-solid state is modelled with the coupling of shear rate and temperature. The stop of Mold Filling attributes to the pressure loss which is caused by the viscosity during the flow of the melt/semi-solid slurry. Pressure loss caused by viscous flow and heat transfer between the alloy and the Mold are calculated and coupled during the Mold Filling of the melt/semi-solid slurry. A pressure-driven Mold Filling model of aluminum alloy melt/semi-solid slurry is established based on steady-state rheological behavior. The model successfully predicts the Filling length of melt/semi-solid slurry in pressure casting processes. Compared with the experimental results, the model can provide a quantitative approach to characterize the pressure-driven Mold Filling ability of aluminum alloy melt. The model is capable of describing the stop Filling behavior of other aluminum alloys in pressure casting processes with corresponding rheological parameters and heat transfer coefficient.
L. James Lee - One of the best experts on this subject based on the ideXlab platform.
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Effect of Carbon Nanofibers on Mold Filling in a Vacuum Assisted Resin Transfer Molding System
Journal of Composite Materials, 2009Co-Authors: Siva Movva, Gang Zhou, Dante Guerra, L. James LeeAbstract:In this article, a new manufacturing method was used to prepare the hybrid composite, wherein carbon nanofibers were sprayed and bonded onto continuous fiber mats instead of pre-mixing them in the polymer resin. The effect of carbon nanofibers on the Mold Filling characteristics in a vacuum assisted resin transfer Molding system was investigated. A simple one-dimensional flow model was used to correlate the permeability and porosity to the Mold Filling time. It was found that the dispersion and loading of the carbon nanofibers affected the permeability and porosity of the reinforcement system, and hence the Mold Filling time.
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Mold Filling and cure modeling of RTM and SRIM processes
Composite Structures, 1994Co-Authors: L. James Lee, W.b. Young, R. J. LinAbstract:This paper is to discuss the modeling and computer simulation techniques of liquid composite Molding processes, i.e. resin transfer Molding (RTM) and structural reaction injection Molding (SRIM). Mold Filling and curing are simulated using control volume/finite element methods. Several case studies are presented. © 1993.
Toru Okabe - One of the best experts on this subject based on the ideXlab platform.
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Mold Filling and microhardness of 1% Fe titanium alloys.
Dental materials journal, 2004Co-Authors: Hideki Sato, Masashi Komatsu, Barbara H. Miller, Hiroshi Shimizu, Hideki Fujii, Toru OkabeAbstract:We examined the Mold Filling capacity and microhardness of two industrial 1% Fe titanium alloys: Super-TIX800TM (Nippon Steel Corp.) (Fe: 0.910%, O: 0.370%, N: 0.005%) and Super-TIX800NTM (Nippon Steel Corp.) (Fe: 0.960%, O: 0.300%, N: 0.041%). Two wedge-shaped acrylic patterns (with 30° or 15° angles) were prepared. Each alloy was cast in a centrifugal casting machine. Mold Filling was evaluated as the missing length between the tip of the casting and the theoretical tip. Vickers hardness of the edge of the castings was also determined. For both angles tested, there were no significant differences (p>0.05) in Mold Filling among these alloys and the control (CP Ti). The results of testing the microhardness near the cast surfaces indicated that the hardened reaction layers on these alloys were thinner at the edge compared to CP Ti.
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Mold Filling of titanium alloys in two different wedge-shaped Molds.
Biomaterials, 2002Co-Authors: Hiroshi Shimizu, T Habu, Yukyo Takada, K. Watanabe, Osamu Okuno, Toru OkabeAbstract:Pure titanium and titanium alloys are potential materials for the fabrication of cast dental appliances. One important factor in producing sound castings is the capacity of the metal to fill the Mold. This study used a wedge-shaped Mold to compare the Mold Filling of titanium with that of conventional dental casting alloys. The metals used were CP Ti, Ti-6Al-7Nb, Ti-6Al-4V, Ti with 1 and 4wt% Cu and ADA Type III gold alloy and an Ni-Cr alloy. The castings were cut into four pieces parallel to the triangular surface. Mold Filling was evaluated as the distance between the tip of the cast wedge and theoretical tip of the triangle. The Mold Filling of the gold alloy was superior compared to all the metals tested, while the Mold Filling of the Ni-Cr alloy was the worst. There were no statistical differences at the 30 degrees marginal angle for all the cast titanium metals. At the sharper 15 degrees angle, CP Ti and Ti-6Al-7Nb was superior to both the Ti-Cu alloys. Although the Mold Filling of titanium was inferior compared to the gold alloy, the data justify the use of titanium for the production of dental appliances.
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Mold Filling of wedge-shaped Ti-Hf alloy castings
Interface Oral Health Science 2007, 1Co-Authors: Hideki Sato, Masashi Komatsu, Osamu Okuno, Masafumi Kikuchi, Toru OkabeAbstract:An object of this study was to examine the Mold Filling capacity of some Ti-Hf alloys. Regardless of the edge angle, the Ti-Hf alloys behaved similar to commercially pure (CP) Ti due to their isomorphous nature of solidifying congruently over the ranges of the alloys examined.
Jens Fische - One of the best experts on this subject based on the ideXlab platform.
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Mold Filling and dimensional accuracy of titanium castings in a spinel based investment
Dental Materials, 2009Co-Authors: Jens Fische, Andreas Ebinge, Tobias T Hagi, Ogna Stawarczyk, Andreas Wenge, Egbe KelleAbstract:OBJECTIVES: Aim of the study was to analyze the Mold Filling capacity and the dimensional accuracy of a spinel-based investment for titanium castings. METHODS: Expansion of the investment in dependence of the preheating temperature was measured in a dilatometer. The degree of transformation of MgO and Al2O3 to spinel (MgAl2O4) was evaluated by means of X-ray powder diffraction. Mold Filling capacity was assessed by casting a grid and calculating the percentage of completed segments. Dimensional accuracy was analyzed by casting a hollow cylinder and measuring the difference between the inner diameter of the resin pattern and the resulting titanium casting. RESULTS: Spinel formation starts at 819 degrees C. Diffraction patterns prove the formation of spinel from MgO and Al2O3. The amount of spinel increases with increasing preheating temperature. The final expansion of the investment at the end of the preheating cycle at 450 degrees C shows a linear correlation to the maximum preheating temperature. The degree of Mold Filling is reciprocal to the preheating temperature. The dimensional accuracy shows a linear correlation to the amount of spinel. Best dimensional accuracy was obtained at about 900 degrees C. After a preheating temperature of 884 degrees C, as recommended by the manufacturer, the cast specimens showed a slightly lower inner diameter as compared to the resin patterns. SIGNIFICANCE: The results suggest that with the spinel investment analyzed an excellent accuracy of titanium castings may be obtained.