ABSTRACT
This article presents a comparative study of WC and CrC coatings deposited by the plasma-enhanced chemical vapor method using the hexacarbonyls of W and Cr as precursors. The measured thicknesses of the WC and CrC coatings are equal to ca. 1.5 µm. The WC coating consists of microcolumns with a conical end, with gaps between the microcolumns up to approximately 100 nm, and their structure is formed by nanoparticles in the shape of globules with a diameter of up to 10 nm. In the case of the CrC coating, a cauliflower structure with gaps ranging from 20 to 100 nm was achieved. The diameter of cauliflower grains is from 50 nm to 300 nm. The C content in the WC and CrC coating is 66.5 at.% and 75.5 at.%. The W content is 1.4 at.% and the Cr content in the CrC coating is 1.2 at.%. The hardness and Young's modulus of the WC coating are equal to 9.2 ± 1.2 GPa 440.2 ± 14.2 GPa, respectively. The coefficients of friction and wear volume of the WC coating are equal to 0.7 and -1.6 × 106/+3.3 × 106 µm3, respectively. The hardness and Young's modulus of the CrC coating are 7.5 ± 1.2 GPa and 280 ± 18.5 GPa, respectively. The coefficients of friction and wear volume of the CrC coating are 0.72 and -18.84 × 106/+0.35 × 106 µm3, respectively.
ABSTRACT
This work is aimed at the development and investigation of the oxidation behavior of ferritic stainless-steel grade AISI 441 and polymer-derived ceramic (PDC) protective coatings. Double-layer coatings of a PDC bond coat below a PDC top coat with glass and ceramic passive fillers' oxidative resistance were studied at temperatures up to 1000 °C in a flow-through atmosphere of synthetic air and in air saturated with water vapor. Investigation of the oxide products formed at the surface of the samples in synthetic air and water vapor atmospheres, at different temperatures (900, 950, 1000 °C) and exposure times (24, 96 h) was carried out on both uncoated steel and steel coated with selected coatings by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The Fe, Cr2O3, TiO2, and spinel (Mn,Cr)3O4 phases were identified by XRD on oxidized steel substrates in both atmospheres. In the cases of the coated samples, m- ZrO2, c- ZrO2, YAG, and crystalline phases (Ba(AlSiO4)2-hexacelsian, celsian) were identified. Scratch tests performed on both coating compositions revealed strong adhesion after pyrolysis as well as after oxidation tests in both atmospheres. After testing in the water vapor atmosphere, Cr ions diffused through the bond coat, but no delamination of the coatings was observed.
ABSTRACT
OBJECTIVES: To describe and explore somatic disease burdens of ageing long-term patients in opioid maintenance treatment (OMT), a unique population emerging in countries offering OMT as a long-term treatment. METHODS: We used data from the Norwegian Cohort of Patient in Opioid Maintenance Treatment and Other Drug Treatment Study (NorComt). 156 patients enrolled for at least three of the past five years provided data during structured interviews, including on chronic conditions, somatic treatment received, mental distress (SCL-25), and treatment satisfaction. A somatic disease burden was calculated from a list measuring the recent severity of 16 somatic complaints. A hierarchical multiple linear regression analysis identified correlates of somatic disease burden. RESULTS: Over half of patients reported at least seven somatic complaints. Reported somatic disease burden was associated with higher mental distress, more chronic conditions, fewer years in OMT, and treatment dissatisfaction. Age was unrelated, and there were few gender differences. These five variables explained 43.6% of the variance in disease burden. CONCLUSION: Long-term OMT patients experience a large range of somatic complaints, and at non-acute levels. As OMT secures longevity for opioid-dependent persons, the clinical focus must be adjusted from acute to chronic care. Providers must address how to optimize health and quality of life while in treatment, as treatment may last for many years.
