Development of Thermomechanical Processes as an Alternative to Grain Refiners in 18 Carat Gold Alloys

The use of grain refiners, such as iridium, in 18 kt gold alloys is a common practice in jewelry industrial applications. The use of these elements leads, however, to an increase in the costs of raw materials and greater attention during the solidification phases and during the refining and recycling of alloys is required. This work aims to demonstrate that through the optimization of thermo-mechanical processes, it is possible to obtain a result comparable to that obtained with refiner in terms of workability, mechanical and aesthetic properties and corrosion behavior. The study focused on evaluating the grain growth in annealing processes after plastic deformation, also examining the casting phase and the effect of the different cooling rates. The samples, after the different thermo-mechanical treatments, were characterized in terms of microstructure, grain size and micro-hardness comparing the results with the ones of an iridium-containing alloy. The results showed that with proper optimization of annealing time is possible to obtain, without grain refiners, gold alloys with properties similar to ones obtained with Iridium as a grain refiner.

Electrochemical behavior of various implantation biomaterials in the presence of various simulated body fluids: An overview

In Modern medicine, metals and alloys are being used as implants. The Corrosion behaviour of various biomaterials under artificial body fluids are being studied. Artificial biomaterials are being implanted inside the human body to replace bone, teeth, etc. Even organs are being medically substituted with different types of metals such as mild steel, carbon steel, Ni-Cr alloy, Fe-Cr alloy, 22 carat Gold,24 carat Gold Tin, etc. due to their biocompatibility. This is achieved by connecting these metals directly with body tissues. The metals tend to corrode when it gets in contact with human body fluids. The body fluids thereby come in direct contact with tissues and the tissues are in contact with the metal thus causing the metal to corrode. And hence the corrosion resistance studies such as polarisation, AC impedance, cyclic voltammetric studies, etc, are being conducted in a medium like artificial blood plasma, artificial urine, artificial salvia, artificial sweat, Hank solution, Ringer solution, etc. The different body fluids are examined in the presence of different implantation metals by electrochemical methods and protective films are formed which are analyzed by various surface analysis techniques such as AFM, FTIR-UV, SEM, etc. The research findings will thereby be very helpful to the medical field.

Poise Is A Dangerous Pest Of Winter Wheat

This article presents the results of scientific research on the biology and harmfulness of the wheat drunkard. Against this pest, insecticides were used in the standard control variant of Karache 10% e.c., 0.07 l/ ha and the biological efficiency was 90.4% 95.6% and 96.8%, in the experimental variant, respectively, when 0.075 l/ha was applied. Carat gold plus 10% e.с. 90.9%, 96.1% wa 97.5%.

Implementasi Metode Fuzzy Sugeno Pada Penentuan Harga Emas 24 Karat pada Kota Medan

Gold is one of the most precious precious metals by the public because gold prices tend to be stable and increase every month, gold investment has also developed quite rapidly. Gold can be invested in various forms such as gold bars and gold in the form of jewelry that has value to add to the wearer's appearance besides that there is also gold in the form of ancient currency coins that have historical value and are usually kept by collectors, gold is one form of investment that is not influenced by trends in society because gold is bought by everyone at any time. The purpose of this study was to determine the determination of the price of 24 carat gold in medan city. In this study, the authors used 3 criteria including demand, quality and price.