Showing 3 results for Powder Metallurgy
S. H. Razavi, Sh. Mirdamadi, M. M. Hormozi,
Volume 8, Issue 1 (3-2011)
Abstract
Abstract: The aim of the present investigation is to study the physical and mechanical characteristics of dental-filling spherical high-copper and silver amalgams and to compare them with a common high-copper domestic unicompositional amalgam. In this study, cylindrical specimens were mechanically condensed according to the ISO 1559:1986 Standard in order to measure the compressive strength, Vickers hardness, static creep and dimensional change on setting. Adding more silver to the amalgam increased its compressive strength, creep resistance and reduced mercury vapor. After 1, 24 and 168h of amalgamation and Modulus of elasticity of specimen S1, the mean hardness and compressive fracture strength were significantly lower than those of . No significant differences were identified for the two alloys in the creep and dimensional changes on setting. It can be concluded that as far as the mechanical properties or corrosion resistance is concerned, the amalgam should be comprised of at least one spherical alloy.
N Parvin, R Derakhshandeh Haghighi, M Naeimi, R Parastar Namin, M. M. Hadavi,
Volume 11, Issue 4 (12-2014)
Abstract
In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct methods: mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I) sintering simultaneously with infiltration process and II) sintering prior to infiltration (pre-sintering process). It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.
N. Aboudzadeh, Ch. Dehghanian, M.a. Shokrgozar,
Volume 14, Issue 4 (12-2017)
Abstract
Recently, magnesium and its alloys have attracted great attention for use as biomaterial due to their good mechanical properties and biodegradability in the bio environment. In the present work, nanocomposites of Mg - 5Zn - 0.3Ca/ nHA were prepared using a powder metallurgy method. The powder of Mg, Zn and Ca were firstly blended, then four different mixtures of powders were prepared by adding nHA in different percentages of 0, 1, 2.5 and 5 %wt. Each mixture of powder separately was fast milled, pressed, and sintered. Then, the microstructure and mechanical properties of the fabricated nanocomposites were investigated. The XRD profile for nanocomposites showed that the intermetallic phases of MgZn2, MgZn5.31 and Mg2Ca were created after sintering and the SEM micrographs showed that the grain size of nanocomposite reduced by adding the nHA. The nano composite with 1wt. % nHA increased the density of Mg alloy from 1.73 g/cm3 to 1. 75 g/cm3 by filling the pores at the grain boundaries. The compressive strength of Mg alloy increased from 295MPa to 322, 329 and 318MPa by addition of 1, 2.5 and 5wt. % nHA, respectively.
