Control and monitoring system prototype for pulse plasma sintering process
Cubic boron nitride is commonly used as a cutting tools material for the sake of its high hardness and wear-resistance. Pulse Plasma Sintering was proposed to decrease the production costs. This method is very attractive for industry, because it significantly decreases the costs of production. The goal of this paper is to present the control system prototype for Pulse Plasma Sintering processes based on programmable logic controller. Only sintering process with carefully controlled parameters allows to restrict the transformation of cBN into hBN and guarantee production of high-quality cubic boron nitride samples. Thus a dedicated control system was developed to control parameters and therefore to improve the production process. This paper presents also a visualisation system which allows the operator to control, monitor and analyze the production process. Prepared application consists of manual and auto operating mode.
Sintering Diamond/Cemented Carbides by the Pulse Plasma Sintering Method
Under the conditions of thermodynamic instability, we produced dense sintered composites built of diamond particles (30 vol%) and a cemented carbide matrix. The composites were consolidated by high-current electric pulses at a temperature of about 1100°C and load of 75 MPa for 5 min. The diamond particles are strongly bound with the cemented carbide matrix, by a transition layer composed of a solid solution of carbon and tungsten in cobalt. No graphite precipitates were found in the sintered composites, as examined by microstructure observations, examinations of the phase composition, and an analysis of the Raman scattering spectra. The hardness of the diamond/cemented carbide was 23 GPa.
Measuring Sheet Resistances of Dielectrics Using Co‐Planar Hydrogel Electrochemical Cells with Practical Applications to Characterize the Protective Quality of Paints on Sculptures
Electrical properties of thin dielectric films at the solid-liquid phase boundary are an important performance characteristic of many devices, coatings and sensors. In this paper, co-polymeric hydrogels of polyacrylic acid co-sulfonic acid, swollen with a salt solution to act as the solid electrolyte, were used to assess interfaces using electrochemical impedance spectroscopy (EIS) in a co-planar geometry. Silane-modified glasses were characterized by the co-planar hydrogel EIS cell and found to be distinguishable based on their surface monolayer chemistry. EIS measurements were also made on primed and painted metal substrates, using both test panels and an outdoor sculpture, Tony Smith's Stinger. The panels were then exposed to accelerated and outdoor weathering and showed degradation on the surface paint layers, which was observable electrochemically using EIS and confirmed visually by SEM. Electrochemical spectral features were compared between data from a standard paint-test cell versus this co-planar hydrogel cell; both cell types were able to measure coating capacitance, providing useful information about the condition of the bulk coating. Yet, sheet resistance (Rs) was a spectral feature seen only by the co-planar hydrogel cell. Thus, it can be concluded that the use of such co-planar hydrogel cells can provide an earlier warning sign to coating degradation and such cells provide a new type of spectral information that is not assessable by the standard geometry.