Effect Of Argon Atmosphere Research Articles

Influence of firing conditions and production methods on fracture strength of titanium-based metal ceramic crowns

Objectives: This study evaluated the effect of argon atmosphere compared with vacuum during porcelain firing on the fracture strength of crowns made of porcelain and electron beam melted (EBM) Ti-6Al-4 V, cast commercially pure titanium or milled commercially pure titanium. Methods: Sixty crown copings of c. p. titanium, Ti-6Al-4 V alloy and porcelain were fabricated using three production techniques. The copings were fired either under vacuum or in an argon gas atmosphere. Specimens were subdivided into groups of cast c. p. titanium, milled c. p. titanium and EBM Ti-6Al-4 V which were further subdivided according to firing modes employing either vacuum or argon gas. The 60 specimens were subjected to cyclic preloading and thermocycling, and were then individually loaded until interface fractured. Differences between the group mean values were calculated using the one-way ANOVA and Tukey’s range test. Two fractured samples from each group were cut with a diamond blade and examined using SEM and EDS for visualization and chemical composition analysis of the fractured interface. Results: The highest mean fracture strength values, though not significant, were recorded for the groups fired in argon atmosphere, and the lowest mean fracture strength values were recorded for the groups fired in vacuum, with one exception. Comparing the two main groups of firing atmosphere, no significant difference could be documented. SEM and EDS analysis indicated clear differences in composition and structure between the groups included in the study. Conclusions: Firing in argon atmosphere does not significantly improve the fracture strength of porcelain bonded to titanium.

Effect of argon atmosphere on the formation of MoSi2 by self-propagating combustion method

Abstract The effect of argon atmosphere on the formation of MoSi2 by self-propagating combustion method has been detailedly investigated in present work by comparing SHS reaction between Mo and Si in argon atmosphere with that in vacuum. The SHS procedure in argon atmosphere could produce higher heating rate and maximum temperature than that in vacuum. The particle size distribution of synthesized products has been studied by light transmission sedimentation method. More homogeneous particle size distribution of the molybdenum disilicide by SHS method in argon atmosphere was achieved than it in vacuum. And it also can be observed in SEM photographs of synthesized products. Compared with SHS method in vacuum, a purer product was indicated by XRD and X-fluorescence analysis results while reaction in argon atmosphere.

Effect of Argon Atmosphere on Self-Absorption of a Spectral Line in Laser Microprobe Analysis

The effect of the reduced argon atmosphere on the self-absorption of a spectrum was studied with the use of a normal laser microprobe by changing the gas pressure and the observation height of spectral lines. At 150 Torr, a spectral line virtually free of self-absorption and a resultant high emission intensity were obtained about 1.5 mm above the sample surface. Using this condition, the linear calibration curve with unit slope was obtained for the analysis of copper (concentration:1–20%) in aluminium samples.

The effect of argon atmospheres on the intensity of certain spectral lines

The use of argon as an environment for the direct current are results in the enhancement of the lines of many elements when compared with helium and argon-helium mixtures. This is particularly true of the more volatile elements. A number of lines have been studied in this regard and the results have been qualitatively grouped as lines definitely, equivocally, and not at all enhanced. In some instances the use of an argon environment for the direct current are markedly increases the sensitivity of analysis with this source.