On the hot pressing of coloured high-gold alloys powder compacts applied to the manufacturing of innovative jewellery items

Abstract

Innovative design through colour has always been a very important feature in decorative items, jewellery inclusive. The use of coloured gold alloys (e.g. red, white, green) in the manufacture of jewellery artifacts is nowadays generalized, and one can often see jewellery items that combine more than a single colour. However, multicoloured jewellery artifacts are generally made of parts produced separately and bonded together in a later step. The ability to produce jewellery sub-components or final pieces using a powder metallurgy process aimed at producing innovative multi-coloured gold jewellery items with colour gradients is explored in this paper. Four 19.2 ct coloured gold powders (yellow, green, red and white) were hot pressed at different times and temperatures and the resulting samples were analyzed in terms of their microstructure, hardness, porosity, microstructure and optical properties. A manufacturing route to obtain multi-coloured jewellery pieces with colour gradients is also presented.

Identifying chemical and physical changes in wide-gap semiconductors using real-time and near ambient-pressure XPS

“…A gold-silver-copper alloy was prepared by the Diamond Centre Wales (DCW Ltd) using injection mold casting with a predicted composition of 75% gold, 15% silver and 10% copper. 21 The sample was then ultrasonically cleaned using acetone, isopropyl alcohol and methanol before mounting in the spectrometer.…”

Powder Metallurgy and Precious Metals: State of the Art and Future Developments

“…Press and sintering is a largely used technology, mainly to medium to simple, axial-symmetric components. Even if the shape limitation of these techniques may hinder their application on precious metals, some specific pressing techniques offer undeniable benefits in terms of properties and processing conditions [5,6]. An example of enhanced sintering techniques are the so-called FAST (Field Assisted Sintering Techniques).…”

On the application of Electro-sinter-forging to the sintering of high-karatage gold powders

“…In the last decades, the high-quality jewelry industry, traditionally based on handcraft abilities, has been facing a rising interest towards new technologies and innovative materials. This renovation, mainly driven by the specific global scenario, is concerning several aspects of the industrial field, such as the introduction of new technologies [1][2][3] and materials [4,5], the exploitation of new design features [6], and the opening towards new markets. When considering product innovation, two different aspects have to be taken into account: material optimization and process enhancement.…”