A numerical model, using the discrete element method, has been developed to quantify specific parameters that are pertinent to the packing behaviour of relatively large, spherical NaCl beads and mixtures of beads of different sizes. These parameters have been compared with porosity and connectivity measurements made on porous aluminium castings made by molten metal infiltration into packed beds...

Background and aims. Because of compromised angulations of implants, the abutments are sometimes prepared. The purpose of this study was to investigate the effect of removing one wall of the implant abutment on the retention of cement-retained crowns. Materials and methods. Four prefabricated abutments were attached to analogues and embedded in acrylic resin blocks. The first abutment was left ...

The process of photopolymer stereo-lithography (SLA) provides a unique opportunity for the rapid prototyping of investment castings having both high surface quality and complex geometry from both ferrous and non-ferrous metals. A specific internal honeycomb structure gives a combination of high pattern stiffness needed for precise replication of geometry by investment shell molds with an extrem...

This study aimed to develop a dental investment for titanium casting. ZrO(2) and Al(2)O(3) were selected as refractory materials to prepare three investments (Codes: A-C) according to the quantity of Zr. Al(2)O(3) cement was used as a binder at a ratio of 15%, they were mixed with special mixing liquid. B1 was used as a control mixed with water. Fundamental examinations were statistically evalu...

T ests for accuracy and other characteristics of elastic impression materials generally fall into one or more categories. These are: (1) Linear tests which measure the material itself (usually unidimensional) .le5 (2) Tests which depend upon the formation and measurement of gypsum dies made from the impression materials. In these tests, the dies are measured, not the impression material itself....

The influence of heat treatment time and temperature on the microstructure and corrosion resistance of cast stainless steel alloys CN3MN (UNS J94651) and CK3MCuN (UNS J93254) were investigated with a combination of microscopy techniques and immersion corrosion testing. The as-cast alloys exhibited significant residual microsegregation of Mo across the dendritic substructure and the presence of ...

Based on results from computational studies and plate casting trials, deficiencies in the steel casting feeding rules as currently published by the Steel Founders’ Society of America (SFSA) were determined. A methodology for the development of improved steel casting feeding rules was established based on the Niyama criterion determined from simulation. Newly developed feeding rules using this m...