Goksel Hizli

Istanbul Technical University · Department of Metallurgical and Materials Engineering

In general, many cast parts require a final surface finish which could be sand blasting, grinding, or machining. In such applications, the cutting tool life is a critical parameter where the mass production rate becomes important. Therefore, in this work, the correlation between melt quality and machin- ability of the high-pressure die-cast Al9Si3C...

Strontium master alloy is widely used in today's aluminum foundries for modification of Al-Si alloys. In this study, Al-Sr master alloy was produced in molten Al alloy directly from strontium carbonate instead of using the pure strontium metal which is difficult to store in the air due to its high oxygen affinity. In a laboratory-scale induction fu...

The carbothermic reduction of celestite is the first step in producing many strontium products. The way materials move in the rotary kiln has an essential effect on the carbothermic reduction efficiency as well as the temperature. In this study, the reduction of celestite ore and excess carbon blend in a laboratory-scale rotary kiln was investigate...

High-pressure die casting is the most suitable method for mass production of Al–Si alloys. The cast parts are typically subjected to machining for the final finish. In this work, the cutting tool life was investigated with regard to the melt quality. The melt cleanliness is defined by reduced pressure test and bifilm index was measured. Since bifil...

Al-Si alloys are widely preferred in the casting industry due to their superior properties. When the coarse silicones are modified, the silicon structure is homogeneously dispersed and higher mechanical properties are achieved. Despite the continuous use of the modification process, there are uncertain points about the working mechanism. A full und...

Al-Si alloys are the most preferred alloys for gravity and high pressure casting. Solid solubility of iron in aluminum is less than 0.05% in equilibrium. Thus, almost all of the iron in the aluminum alloys forms the second phase particles. Fe intermetallics occur due to the limited resolution of aluminum and steel systems. As the Fe level increases...

The usage of secondary aluminum has a large volume in the industry due to the economic beneficial. The effect of degassing on the melt quality, microstructure and mechanical properties of secondary alloys were studied in this article. Fluidity and melt quality are have a important roles on mold filling. Fluidity was examined with new-design mold an...

For comparison the effects of the domestic sr-master alloy and commercial master alloy additions on the microstructure and mechanical properties of strontium (Sr) on Al-9Si-0.3Mg alloy were investigated in the present work. Microstructure was examined with optical microscope (OM) and SEM-EDS. Hardness and UTS tests were performed. Analysis of mean...

Al-Si alloys are mostly used in casting industry for automotive parts. In this alloy, silicon need to be modified to obtain fine fibrous particles instead of coarse needles. Strontium master alloys have been used as modifier in Al-Si alloys for decades [1,2]. The modification was first discovered in 1921 by Aladar Pacz and his unique method was pat...

In this study, strontium carbonate precipitation from strontium sulphide solution was investigated. Experimental study was carried out to determine the effects of precipitation period (5, 15, 30, 60 min), sodium carbonate concentration (1, 1.1, 1.25, 1.5, and 2M) and temperature (25, 55, 75°C). The SrS solution used in the experiments was obtained...

Strontium carbonate is commonly produced in high purity by the black ash method. In the last stage of this multi-step method, the SrCO3 precipitation process uses sodium carbonate, carbon dioxide, etc. In this study, ammonium carbonate was used as a carbonate source in the SrCO3 precipitation of the SrS solution and the effects of ammonia and hydro...

Effect of the high energy ball milling on the direct conversion of celestite to strontium carbonate (SrCO3) was studied. Celestite ore was ground by a planetary ball mill with sodium carbonate (Na2CO3) solution. Experimental study carried out to determine the effects of milling time (5, 10, 15, 30, 60, and 120 min) and Na2CO3 concentration (1, 1.25...

Celestite is the main source of strontium containing chemicals and metallic strontium. Unlike other sulfate containing minerals, celestite is not soluble in water. Further processing of SrSO4 requires conversion to water-soluble strontium sulfide (SrS). In this study, solubility of SrS in distilled water is investigated. SrS used in experimental st...

Celestite ore (SrSO4) is used as raw material for the production of strontium compounds. The aim of this study is to develop a new and efficient strontianite (SrCO3) production method. Strontianite was obtained from domestic celestite concentrate with direct conversion method in which celestite reacts with \( {{\text{CO}}_{3}}^{2 - } \) and \( {{\t...

Turkish celestite ore was roasted in a lab scale rotary kiln furnace with metallurgical coke. Coke and celestite were mixed; the product contained 32% coke which is more than the stoichiometric requirement. 100 g of the mixed product was fed to a rotary furnace at 35 g/min. Temperature (1000 and 1100 °C), rotation speed (2.5, 5 and 10 rpm) and the...

In this study, effect of mechanical activation in planetary ball mill and disc mill, on carbothermic reduction of celestite ore with coke was investigated. Celestite ore (96% SrSO4) from Sivas district was blended with excess metallurgical coke and mechanically activated for 1, 5, 15 and 45 min. Mechanically activated blends were analyzed by Partic...

Same size of Al-Cu alloy samples were heaten at 535ºC. And these samples quenched with Jominy Method with different parameters like time and quenching solutions as 15,30,60 min and moving water, static water and static oil. Then samples residual stresses were examined by Thermal Analysis and hardnesses which depending on distance examined by BSD. H...