The Effect of Coating Patterns with Spinel-Based Investment on the Castability and Porosity of Titanium Cast into Three Phosphate-Bonded Investments

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effect of mold temperature on castability of CPTi and Ti-6Al-4V castings into phosphate bonded investment materials

Objective. The aim of this study was to evaluate the castability of CP titanium and Ti-6Al-4V alloy castings into Rematitan Plus investment at three different mold temperatures.Methods. A nylon mesh pattern (20 mm with 64 squares and wire of 0.7 mm in diameter) was used for the castability testing. Initially, an image of the wax pattern was obtained by means of a digital camera and the total extension of filaments (mm) was then measured, using the Leica Qwin image analysis system. The mesh sprued was placed in the Rematitan Plus investment material and the castings were made in a Discovery Plasma machine at three different mold temperatures: 430 degrees C (control group), 480 degrees C or 530'C. Ten castings were made for each temperature. The images of the castings were analyzed (Leica Qwin) and the castability index determined by the number of the completely cast segments as a percentage of the wax pattern. Data were analyzed by two-way ANOVA and Tukey's multiple comparison test (a = 0.05) using materials and temperatures as discriminating variables.Results. The Ti-6Al-4V alloy (60.86%) presented a better castability index than CP Ti (48.44%) (p < 0.000001). For CP Ti, the temperature of 530 degrees C (23.96%) presented better castability than at other temperatures, 480 degrees C (14.66%) and 430 degrees C (12.54%), with no difference between them (p < 0.001). For Ti-6Al-4V alloy, there was a statistically significant difference among the three temperatures: 530 degrees C (28.36%) > 480 degrees C (19.66%) > 430 degrees C (15.97%) (p < 0.002).Significance. Within the limitations of this study, the increase in the mold temperature of the Rematitan Plus investment resulted in a better castability index for both materials, and Ti-6Al-4V presented a better castability index than CP Ti. (c) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

THE INFLUENCE of SHORT-HEATING-CYCLE INVESTMENTS on THE QUALITY of COMMERCIALLY PURE TITANIUM CASTINGS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito das técnicas de fusão sobre a fluidez de ligas do sistema cobre-alumínio.

It was evaluated the castability of four copper-aluminium alloy according the melting casting method used. The specimens were made using polyester mesh screen, with 11 x 11 filaments of 0.26 mm thick, fixed along of two adjacent edges in wax bar, with the sprue attached at their junction. The alloys were in an electrical casting machine and a centrifugal casting machine with an air/gas torch. The castability values were obtained by the percentage of completed segments of the resulting cast alloy screen. It was verified that the use of the electrical casting machine produced higher castability values to the copper-aluminium alloys than those produced by a centrifugal casting machine with an air/gas torch.

Efeito de um revestimento com processamento rápido para fundição de titânio na camada de reação, porosidade interna, fluidez, rugosidade superficial e adaptação marginal de Copings

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O efeito da técnica de inclusão para fundição de titânio CP na fluidez, rusogidade, camada de reação e desajuste marginal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A Quality Assessment of Titanium Castings Produced in an Experimental Short-Heating-Cycle Investment

The aim of this study was to evaluate the quality of casting produced in an experimental short-term heating-cycle investment. Thus, reaction layer and castability of titanium casting using an experimental spinel-based investment (VR) with short heating cycle were compared with the commercial short-heating-cycle spinel-based investment Trinell (TR), the silica-phosphate-based investment Rematitan Plus ( RP), and the conventional spinel-based investment Rematitan Ultra (RU). VR has polymeric fibers added to inorganic particles. Reaction layer assessments were carried out using Vickers hardness and elemental analysis using dispersive X-ray microanalysis (EDX). Mesh patterns were used for castability test, and powder characterization was made by scanning electron microscopy (SEM). Hardness evaluation showed no difference among the investments between 100 and 200 mu m. The most important contaminant element for VR, TR, and RU was oxygen. Higher levels of mold filling were found for TR, VR, and RU compared with that obtained with RP. The quality of castings, characterized by means of the assessments of reaction layer and castability, made from the VR was similar to the commercial investments TR and RU but superior to the RP.