High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr-SiN coatings with Si contents of 24-30 at.% exhibited the hardness of Si 3 N 4 , which was higher than those of the middle-Si-content (19 at.%) coatings. In this study, the bonding characteristics of the constituent elements of Zr-SiN coatings were evaluated through X-ray photoelectron spectroscopy. Results indicated that the Zr 3d 5/2 levels were 179.14-180.22 and 180.75-181.61 eV for the Zr-N bonds in ZrN and Zr 3 N 4 compounds, respectively. Moreover, the percentage of Zr-N bond in the Zr 3 N 4 compound increased with increasing Si content in the Zr-SiN coatings. The Zr-N bond of Zr 3 N 4 dominated when the Si content was >24 at.%. Therefore, high Si content can stabilize the Zr-N compound in the M 3 N 4 bonding structure. Furthermore, the thermal stability and chemical inertness of Zr-SiN coatings were evaluated by conducting thermal cycle annealing at 270 • C and 600 • C in a 15-ppm O 2-N 2 atmosphere. The results indicated that a Zr 22 Si 29 N 49 /Ti/WC assembly was suitable as a protective coating against SiO 2-B 2 O 3-BaO-based glass for 450 thermal cycles.
In this study, the fatigue crack growth rate (FCGR) of a Ti15V3Cr3Al3Sn (Ti-15-3) alloy, which was aged at a temperature range of 371 to 593°C, was measured in air at room temperature. The specimen aged at 371°C showed clear serrations in the crack growth curve at a stress ratio (R) of 0.1, and it also exhibited a larger Paris law gradient than the other aged specimens at R = 0.5. The peak-aged (426°C aged) specimen had the highest FCGR of the specimens, regardless of the stress ratio. A gradual decrease in the FCGRs with increasing aging temperature, from 482 to 593°C, was observed for the over-aged specimens. Cleavage-like fracture was more likely to occur in the under-and peak-aged specimens as compared to the transgranular fatigue in the over-aged specimens. It seemed that the coarse ¡ platelets with lowered hardness in the over-aged specimens resulted in a higher resistance to fatigue crack growth in the Ti-15-3 alloy.
In this study, the fatigue crack growth rates (FCGRs) of Ti-15V-3Cr-3Al-3Sn alloy aged in the temperature ranges from 426 to 593 oC for 8 hrs was determined at stress ration of 0.1 or 0.5. The results of fatigue crack growth tests revealed the FCGRs decreased with increasing aging temperature. Generally, the 426oC aged specimen had the highest FCGRs among the specimens being tested, regardless of stress ratio. It was noted obvious increase in FCGRs occurred for the 482oC aged specimen at stress ratio of 0.5. Fatigue fracture appearance of various specimens tested in air exhibited predominantly transgranular fatigue fracture with coarse stripes for the specimens aged at/above 538oC. Intergranular fracture was more likely to be found in the 426oC aged specimen, and for the A482 specimen tested at high stress ratio.
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