Increasing the silicon carbide content in laser sintered reaction bonded silicon carbide

© 2017 The American Ceramic Society. Additive manufacturing (AM) of ceramics is in its infancy. Compared to conventional shaping processes, AM is more economical for small series and comes with a higher degree of design freedom. AM technologies like laser sintering can be used to produce preforms for reaction bonded silicon carbide (RBSC) parts. After laser sintering, liquid silicon infiltration is carried out and the preforms are transformed into dense RBSC parts, also known as Si-infiltrated SiC (SiSiC). These parts, however, contain residual Si which has a detrimental effect on mechanical and thermal properties. The current work focusses on creating an RBSC component with high SiC and low residual Si contents. This is done by impregnating the laser sintered preforms with a carbon precursor phenolic resin. The carbon provided by the resin reacts with the Si melt during infiltration to form a secondary (reaction formed) SiC. The result is a fully dense RBSC component with up to 75 vol% SiC.status: publishe

A strategy for the identification of plants in illegal pharmaceutical preparations and food supplements using chromatographic fingerprints

The detection of regulated and forbidden herbs in pharmaceutical preparations and nutritional supplements is a growing problem for laboratories charged with the analysis of illegal pharmaceutical preparations and counterfeit medicines. This article presents a feasibility study of the use of chromatographic fingerprints for the detection of plants in pharmaceutical preparations. Fingerprints were developed for three non-regulated common herbal products-Rhamnus purshiana, Passiflora incarnata L. and Crataegus monogyna-and this was done by combining three different types of detection: diode-array detection, evaporative light scattering detection and mass spectrometry. It is shown that these plants could be detected in respective triturations of the dry extracts with lactose and three different herbal matrices as well as in commercial preparations purchased on the open market</p