CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by u...CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by using X-ray diffraction,scanning electron microscopy,differential scanning calorimetry,thermal gravimetric analysis and nanoindentation.The structural transformation of single phase cubic Cr_(0.42)Al_(0.58)N and Cr_(0.39)Al_(0.56)Y_(0.05)N coatings to cubic−wurtzite mixed Cr_(0.32)Al_(0.56)Y_(0.12)N coating leads to a drop in hardness from(30.2±0.7)GPa of Cr_(0.42)Al_(0.58)N and(32.0±1.0)GPa of Cr_(0.39)Al_(0.56)Y_(0.05)N to(25.2±0.7)GPa of Cr_(0.32)Al_(0.56)Y_(0.12)N.The incorporation of 5 at.%Y retards the thermal decomposition of CrAlN,verified by the postponed precipitation of w-AlN and N-loss upon annealing.Correspondingly,Cr_(0.39)Al_(0.56)Y_(0.05)N coating consistently exhibits the highest hardness value during thermal annealing.Nevertheless,alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN.展开更多
Beef tallow is a byproduct of the slaughter industry. As a consequence, meat producer countries obtain a high amount of this low value-added fatty material. In Uruguay, it is generally used for food purposes or for bi...Beef tallow is a byproduct of the slaughter industry. As a consequence, meat producer countries obtain a high amount of this low value-added fatty material. In Uruguay, it is generally used for food purposes or for biodiesel production. Globally, around half of the beef tallow produced worldwide is used for the manufacturing of food. To the best of our knowledge there are no published studies concerning the stability of beef tallow when exposed to high temperatures. The aim of this work was to study some Uruguayan beef tallow brands and compare its stability with that of the most frequently used frying oils in Uruguay （sunflower high oleic, rice bran and sunflower oil） to assess its suitability for frying. Stability was assessed by the oxidative stability index and thermoxidation in absence of food. Even though beef tallow＇s inherent stability indicated that it should be highly stable to oxidation, the majority of the analyzed samples exhibited a similar or lower stability than sunflower high oleic. This might be explained by a different composition in pro-oxidants and/or antioxidants between the beef tallows and the oils. According to the thermoxidation assays, which are carried out in similar conditions to those of a frying process, three of the beef tallow samples, sunflower high oleic and rice bran oil would be similarly suitable for frying, while sunflower oil and the other two samples of beef tallow evidenced a lower thermoxidative stability, thus not being recommended for this use.展开更多
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51775560).
文摘CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by using X-ray diffraction,scanning electron microscopy,differential scanning calorimetry,thermal gravimetric analysis and nanoindentation.The structural transformation of single phase cubic Cr_(0.42)Al_(0.58)N and Cr_(0.39)Al_(0.56)Y_(0.05)N coatings to cubic−wurtzite mixed Cr_(0.32)Al_(0.56)Y_(0.12)N coating leads to a drop in hardness from(30.2±0.7)GPa of Cr_(0.42)Al_(0.58)N and(32.0±1.0)GPa of Cr_(0.39)Al_(0.56)Y_(0.05)N to(25.2±0.7)GPa of Cr_(0.32)Al_(0.56)Y_(0.12)N.The incorporation of 5 at.%Y retards the thermal decomposition of CrAlN,verified by the postponed precipitation of w-AlN and N-loss upon annealing.Correspondingly,Cr_(0.39)Al_(0.56)Y_(0.05)N coating consistently exhibits the highest hardness value during thermal annealing.Nevertheless,alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN.
文摘Beef tallow is a byproduct of the slaughter industry. As a consequence, meat producer countries obtain a high amount of this low value-added fatty material. In Uruguay, it is generally used for food purposes or for biodiesel production. Globally, around half of the beef tallow produced worldwide is used for the manufacturing of food. To the best of our knowledge there are no published studies concerning the stability of beef tallow when exposed to high temperatures. The aim of this work was to study some Uruguayan beef tallow brands and compare its stability with that of the most frequently used frying oils in Uruguay （sunflower high oleic, rice bran and sunflower oil） to assess its suitability for frying. Stability was assessed by the oxidative stability index and thermoxidation in absence of food. Even though beef tallow＇s inherent stability indicated that it should be highly stable to oxidation, the majority of the analyzed samples exhibited a similar or lower stability than sunflower high oleic. This might be explained by a different composition in pro-oxidants and/or antioxidants between the beef tallows and the oils. According to the thermoxidation assays, which are carried out in similar conditions to those of a frying process, three of the beef tallow samples, sunflower high oleic and rice bran oil would be similarly suitable for frying, while sunflower oil and the other two samples of beef tallow evidenced a lower thermoxidative stability, thus not being recommended for this use.
