Ultrasonic cavitation erosion of gas nitrided Ti-6Al-4V alloys.
Ultrasonic cavitation erosion experiments were performed on Ti-6Al-4V alloys samples in annealed, nitrided and nitrided and subsequently heat treated state. The protective oxide layer formed as a result of annealing and heat treatment after nitriding is eliminated after less than 30 min cavitation time, while the nitride layer lasts up to 90 min cavitation time. Once the protective layer is removed, the cavitation process develops by grain boundary erosion, leading to the expulsion of grains from the surface. The gas nitrided Ti-6Al-4V alloy, forming a TixN surface layer, proved to be a better solution to improve the cavitation erosion resistance, compared to the annealed and nitrided and heat treated state, respectively. The analysis of the mean depth of erosion rate at 165 min cavitation time showed an improvement of the cavitation erosion resistance of the nitrided samples of up to 77% higher compared to the one of the annealed samples.
Synergistic effect of ultrasonic cavitation erosion and corrosion of WC-CoCr and FeCrSiBMn coatings prepared by HVOF spraying.
The high-velocity oxygen-fuel (HVOF) spraying process was used to fabricate conventional WC-10Co-4Cr coatings and FeCrSiBMn amorphous/nanocrystalline coatings. The synergistic effect of cavitation erosion and corrosion of both coatings was investigated. The results showed that the WC-10Co-4Cr coating had better cavitation erosion-corrosion resistance than the FeCrSiBMn coating in 3.5 wt.% NaCl solution. After eroded for 30 h, the volume loss rate of the WC-10Co-4Cr coating was about 2/5 that of the FeCrSiBMn coating. In the total cumulative volume loss rate under cavitation erosion-corrosion condition, the pure cavitation erosion played a key role for both coatings, and the total contribution of pure corrosion and erosion-induced corrosion of the WC-10Co-4Cr coating was larger than that of the FeCrSiBMn coating. Mechanical effect was the main factor for cavitation erosion-corrosion behavior of both coatings.
“Family” Support for Family Violence: Exploring Community Support Systems for Lesbian and Bisexual Women Who Have Experienced Abuse
ABSTRACT “Family” is a euphemistic term that lesbian, gay, bisexual, and transgender (LGBT) people use among ourselves to designate membership in lesbian, gay, bisexual, and transgender communities. Ironically, this “family” may be the most sought, yet least successful, support for dealing with the intimate partner violence that occurs within LGBT families. This study of 11 lesbian and bisexual women's experiences seeking support revealed several tiers of unmet needs within the LGBT community. They rarely used services in the general community, although these services are often the focus of both criticism and efforts to build support systems for LGBT victim/survivors. A model presents the different stages and potential sources of support.