A theoretical and experimental study has been carried out on flow, dissolution, and precipitation in porous media. Flow experiments were performed on linear carbonate cores using acidic ferric chloride solutions. Dissolution of the carbonate by the acid causes an increase in the solution pH, thereby precipitating ferric hydroxide. This precipitate plugs up the pore throats in the medium and inc...

conclusions the castings fabricated from the ringless technique with non-precious alloy are acceptable. this investing system is useable for the fabrication of fixed restorations. results after statistical evaluation, the following results were obtained: the mean vertical margin discrepancy for conventional investing was 156.72 ± 64.67µ; for the ringless technique it was 117.3 ± 26.77µ; and for...

A two-year program was conducted to develop and commercially manufacturing technologies to: • Enable significant reductions in the costs of castings, • Increase the complexity and dimensional accuracy of castings, and • Reduce the development times for delivery of high quality castings. implement selected casting The industry-led R&D project was cost shared with NASA's Aerospace Industry Techno...

The Vickers hardness of the cross-sectioned area of titanium castings made from an experimental resin-bonded calcia investment and three commercial investments was evaluated. The microstructure and element distribution of the surface zone were analyzed using an EPMA. The results showed that the high hardness of the casting surface could be decreased using the experimental investment. The hardne...

To evaluate a Ni-43.5wt%Ti alloy as a new alloy for cast clasp, the fatigue properties of its castings were examined and compared with those of Co-Cr and Type IV Au alloys castings. The Ni-Ti alloy was cast into a phosphate-bonded investment mold using an argon-arc melting and pressure casting machine. The Ni-Ti alloy castings showed superelasticity in bending tests. Fatigue tests were carried ...

Increasing use of aluminum shape castings in automotive and aerospace industries has drawn great attention to fatigue properties of cast aluminum components. The fatigue resistance of aluminum castings strongly depends upon the presence of casting flaws and characteristics of microstructural constituents. The existence of casting flaws significantly reduces fatigue crack initiation life. In the...

Patients who cannot tolerate total coverage of the hard palate or whose maxillary arches are poorly formed, because of congenital, developmental or surgical defects, may be unable to wear a conventional complete denture. These patients can be successfully treated with implant-supported prostheses that cover only a minimal amount of palatal tissue. With spark-eroded castings, very precise restor...

-In this paper a three-phase model (liquid, solid and gas) of the mushy zone for investigation of porosity formation in solidifying castings is developed. This model takes into account the release of the dissolved gas from the alloy as well as heat transfer and interdendritic fluid flow in the mushy zone. An important aspect of this work is related to accounting for the term describing porosity...

A comprehensive methodology that takes into account alloy solidification, shrinkage-driven interdendritic fluid flow, hydrogen precipitation, and porosity evolution has been developed for the prediction of microporosity fraction in aluminum A356 alloy castings. The mathematical models presented are implemented in a computational framework consistent with those of commercial casting codes, allow...

Primljeno (Received): 2011-11-07 Prihvaćeno (Accepted): 2012-03-15 Original scientific paper Abstract: Pressure die casting is the method used for forcing molten metal into mould cavities under high pressure and at high speed (10 100 m.s). Pressure die casting is a highly productive method of casting parts with low dimensions tolerance and high surface quality. From the point of view of product...