Search Results (5)

Of the salmon sold in China’s consumer market, 92% was labelled as Norwegian salmon, but was in fact was mainly imported from Chile. The aim of this study was to establish an effective method for discriminating the geographic origin of imported salmon using two fingerprint approaches, Near-infrared (NIR) spectroscopy and mineral element fingerprint (MEF). In total, 80 salmon (40 from Norway and 40 from Chile) were tested, and data generated by NIR and MEF were analysed via various chemometrics. Four spectral preprocessing methods, including vector normalization (VN), Savitzky Golay (SG) smoothing, first derivative (FD) and second derivative (SD), were employed on the raw NIR data, and a partial least squares (PLS) model based on the FD + SG9 pretreatment could successfully differentiate Norwegian salmons from Chilean salmons, with a R² value of 98.5%. Analysis of variance (ANOVA) and multiple comparative analysis were employed on the contents of 16 mineral elements including Pb, Fe, Cu, Zn, Al, Sr, Ni, As, Cr, V, Se, Mn, K, Ca, Na and Mg. The results showed that Fe, Zn, Al, Ni, As, Cr, V, Se, Ca and Na could be used as characteristic elements to discriminate the geographical origin of the imported salmon, and the discrimination rate of the linear discriminant analysis (LDA) model, trained on the above 10 elements, could reach up to 98.8%. The results demonstrate that both NIR and MEF could be effective tools for the rapid discrimination of geographic origin of imported salmon in China’s consumer market. Full article

Cutting tools have long been coated with an AlCrN hard coating system that has good mechanical and tribological qualities. Boron (B) and vanadium (V) additions to AlCrN coatings were studied for their mechanical and tribological properties. Cathodic multi-arc evaporation was used to successfully manufacture the AlCrBN and AlCrVN coatings. These multicomponent coatings were applied to the untreated and plasma-nitrided surfaces of HS6-5-2 and H13 steels, respectively. Nanoindentation and Vickers micro-hardness tests were used to assess the mechanical properties of the materials. Ball-on-flat wear tests with WC-Co balls as counterparts were used to assess the friction-wear capabilities. Nanoindentation tests demonstrated that AlCrBN coating has a higher hardness (HIT 40.9 GPa) than AlCrVN coating (39.3 GPa). Steels’ wear resistance was significantly increased by a hybrid treatment that included plasma nitriding and hard coatings. The wear volume was 3% better for the AlCrBN coating than for the AlCrVN coating on H13 nitrided steel, decreasing by 89% compared to the untreated material. For HS6-5-2 steel, the wear volume was almost the same for both coatings but decreased by 77% compared to the untreated material. Boron addition significantly improved the mechanical, tribological, and adhesive capabilities of the AlCrN coating. Full article

This study focuses on a comparative analysis of AlCrXN (X = Mo or V) coatings with the reference AlCrN coating via arc ion plating technique (AIP). The XRD and XPS results showed that the AlCrXN coatings were mainly composed of fcc-(Cr,Al)N solid solution phases. Both the AlCrMoN and AlCrVN coatings exhibited much higher hardness and adhesive strength than the AlCrN coating. The addition of Mo or V decreased the coefficient of friction (COF) and wear rate, which was due to the formation of lubricant oxides containing Mo or V on the coating surfaces. The cutting results showed that abrasive wear, adhesive wear, and oxidation wear were the main wear mechanisms for the coated tools at the cutting speeds of 60 m/min and 94 m/min. The addition of Mo or V dramatically improved the cutting performance of AlCrXN-coated tools by increasing the anti-wear ability due to the high hardness and the formed lubricant VO_x or MoO_x films. Full article

Molds made of tool steels used in aluminum high-pressure die casting should routinely withstand tens of thousands of injection cycles, but repeated loading and temperature spikes result in their frequent premature wear. Extending their lifetime could be sought by nitriding or application of coatings of even higher hardness or both. Therefore, in the present experiment the arc-deposited Cr/(CrN)/n^x(CrN/CrAlN)/m^x(CrAlN/VN) or Cr/(CrN)/n^x(CrN/TiAlN)/m^x(TiAlN/VN) nano-multilayer stacks were deposited on glow discharge nitrided X40CrMoV5.1 steel. The scanning and transmission electron microscopy backed by Energy Dispersive X-ray Spectroscopy measurements of local chemical composition helped to confirm that the coatings are built of nanolayers of respective nitrides of period less than 10 nm. They also showed that droplets being characteristic for arc deposition method were enriched either in chromium, aluminum or vanadium but not in titanium. Both coatings presented comparable hardness of ~25 GPa, but the one covered with TiAlN/VN was roughly twice as wear resistant as the CrAlN/VN. Simultaneously, they were ~200 and ~100 more wear resistant than X40CrMoV5.1reference steel. Full article

A novel medium manganese (MMn) steel with additions of Cr (18%), Ni (5%), V (1%), and N (0.3%) was developed in order to provide an enhanced corrosion resistance along with a superior strength–ductility balance. The laboratory melted ingots were hot rolled, cold rolled, and finally annealed at 1000 °C for 3 min. The recrystallized single-phase austenitic microstructure consisted of ultrafine grains (~1.3 µm) with a substantial amount of Cr- and V-based precipitates in a bimodal particle size distribution (100–400 nm and <20 nm). The properties of the newly developed austenitic MMn steel X20CrNiMnVN18-5-10 were compared with the standard austenitic stainless steel X5CrNi18-8 and with the austenitic twinning-induced plasticity (TWIP) steel X60MnAl17-1. With a total elongation of 45%, the MMn steel showed an increase in yield strength by 300 MPa and in tensile strength by 150 MPa in comparison to both benchmark steels. No deformation twins were observed even after fracture for the MMn steel, which emphasizes the role of the grain size and precipitation-induced change in the austenite stability in controlling the deformation mechanism. The potentio-dynamic polarization measurements in 5% NaCl revealed a very low current density value of 7.2 × 10⁻⁴ mA/cm² compared to that of TWIP steel X60MnAl17-1 of 8.2 × 10⁻³ mA/cm², but it was relatively higher than that of stainless steel X5CrNi18-8 of 2.0 × 10⁻⁴ mA/cm². This work demonstrates that the enhanced mechanical properties of the developed MMn steel are tailored by maintaining an ultrafine grain microstructure with a significant amount of nanoprecipitates, while the high corrosion resistance in 5% NaCl solution is attributed to the high Cr and N contents as well as to the ultrafine grain size. Full article