Engineering Commons^™

Mechanism Of Siliconizing Of Molybdenum And Tantalum By Vapor Deposition, Gordon Pu Kong Chu

Doctoral Dissertations

"Molybdenum and tantalum were siliconized in an enclosed system by the hydrogen reduction of silicon tetrachloride with induction heating between 900°C and 1450°C.

The siliconizing process was primarily influenced by the gaseous composition, temperature, time, molar flow ratio (SiCl₄/H₂), geometrical shape and ionization charges. The rate of siliconizing, measured as the weight gain by the fused quartz helix balance, generally follows a parabolic law, y = k t^1/2, where y = weight gain, t = time, and k = rate constant. The activation energy is estimated at 21.6 k cal/mole for siliconizing of molybdenum. …

Lattice Parameters, Thermal Expansion Coefficients, Densities, And Imperfections In Silver And In The Alpha-Phase Of The Silver-Indium System, Samir Moustafa Riad

Doctoral Dissertations

“An investigation of structure insensitive properties (lattice parameters, thermal expansion coefficients, densities, and imperfections) of silver and the α-phase of the silver-indium system was suggested by the desirable uses for silver and its indium alloys.

Both silver and indium used were 99.999 per cent pure. The silver-indium alloys were prepared by melting both metals inside evacuated and sealed fused quartz tubes. The solidified alloys were annealed and then examined by X-ray diffraction for homogeneity.

This experimental work is divided into three main parts:-

I. X-ray diffraction investigation to determine the solid solubility limit of the Ag-In α-phase at 25° C, …

A Thermodynamic Study Of The Zirconium-Sulfur, Titanium-Sulfur And Hafnium-Sulfur Systems In The Disulfide-Trisulfide Region, Norbert Achilles Vermaut

Doctoral Dissertations

"A static method was used to study the equilibria which exist between the higher sulfides of zirconium and sulfur at temperatures from 700° to 1000 °C. Both disulfide and trisulfide have been identified by chemical analysis and X-ray diffraction. There exists a two-phase region of 'ZrS₂' and 'ZrS₃'. The composition limit of the homogeneous disulfide phase appears to exist between ZrS_1.90 and ZrS_2.00. The lower composition limit of the homogeneous region of the trisulfide phase was established as ZrS_2.75.

An experimental method of Blitz and co-workers, i.e., the use of evacuated …