The Properties of Cr-Al-N Based Coatings Formed on AISI D2 Steel by Thermo-Reactive Diffusion Technique

In this study, chromium aluminum nitride coating was applied on pre-nitrided AISI D2 steel by the thermo-reactive deposition technique in a powder mixture consisting of ferrochromium, aluminum, ammonium chloride, and alumina at 1000C for 2 h. Steels were gas nitrided for the purpose to enrich the surfaces with nitrogen of the steels in a nitrogen and ammonia atmosphere at 560C for 8 h. The effect of aluminum content in the powder mixture on the Cr-Al-N layer properties was investigated. The coated samples were characterized by X-ray diffraction analysis, scanning electron microscope, and micro-hardness tests. Chromium aluminum nitride layer formed on the pre-nitrided AISI D2 steel was compact and homogeneous. Electron dispersive spectrometer results showed that coating layer includes chromium, aluminum, and nitrogen. X-ray studies showed that the phases formed in the coating layers on the steel surfaces are $Cr_2N$, $(Cr,Fe)_2N_{1-x}$, $AlN$, and $Fe_2N$. The depth of the Cr-Al-N layer ranged from 10.01 ± 1.2 to 13.2 ± 1.7 μm, depending on the aluminum content. The hardness of the coated layers produced on AISI D2 steel are changing from 1743 ± 150 $HV_{0.01}$ to 2067 ± 160 $HV_{0.01}$ depending on bath compositions

Wear Behavior of TiAlN and CrAlN Coatings Deposited by TRD Process on AISI D2 Steel

The wear properties of uncoated, chromium aluminum nitride (CrAlN) and titanium aluminum nitride (TiAlN) coated AISI D2 steel were investigated and compared using ball-on-disc method at 0.3 m/s sliding speed and under the loads of 2.5 N, 5 N, and 10 N against $Si_3N_4$ ball as a counter material. Steel samples were nitrided at 575C for 8 h in the first step of the coating process, and then titanium aluminum nitride coating and chromium aluminum nitride were performed by thermoreactive deposition (TRD) process at 1000C for 2 h. Coated samples were characterized by X-ray diffraction analysis, scanning electron microscopy, microhardness, and ball on disk wear tests. The results of friction coefficient and wear rate of the tested materials showed that the TiAlN coating presents the lowest results

Corrosion Behavior of Nitride and Cr-Al-N Coatings Formed on AISI D2 Steel

In the present work, the corrosion behavior of Cr-Al-N coating formed on the pre-nitrided AISI D2 cold work tool steel by thermo-reactive diffusion technique in the powder mixture consisting of ferro-chromium, aluminum, ammonium chloride and alumina at 1000C for 2 h was investigated. The phases formed in the coating layers were $Cr_2N$, $(Cr,Fe)_2N_{1-x}$, $AlN$, and $Fe_2N$ which were confirmed by X-ray diffraction analysis. The uncoated, nitrided, and Cr-Al-N coated specimens were placed in corrosive media (3.5 wt% salt solution). A standard saturated calomel electrode was used as a reference and graphite as a counter or auxiliary electrode. The effectiveness of the coatings in preventing corrosion was tested in the NaCl solution by electrochemical impedance studies using the Nyquist plots and potentiodynamic studies as well. Conclusively, the application of nitride and Cr-Al-N layers on AISI D2 steel increased its surface hardness and corrosion resistance. The corrosion resistance of Cr-Al-N coatings is higher than that of uncoated and nitrided steels

Corrosion Properties of CrAlN and TiAlN Coatings Deposited by Thermoreactive Deposition Process

In the present study, the corrosion behaviors of chromium aluminum nitride (CrAlN) and titanium aluminum nitride (TiAlN) coatings deposited on AISI D2 steel samples are reported. Steel samples were pre-nitrided at 575C for 8 h in the first step of the coating process, and then TiAlN and CrAlN coatings were performed by thermoreactive deposition process in a powder mixture consisting of alumina, ammonium chloride, aluminum and ferrous titanium or ferrous chromium for TiAlN or CrAlN, respectively. Coating treatments were realized at 1000C for 2 h. Coated samples were characterized by X-ray diffraction analysis, optical microscopy, scanning electron microscopy, and microhardness tester. The corrosion properties of uncoated and coated samples were characterized by potentiostatic polarization test. CrAlN and TiAlN coated steel specimens exhibited the higher corrosion resistance than uncoated steels in a 0.5 M NaCl solution

Pneumococcal and influenza vaccination status of hospitalized adults with community acquired pneumonia and the effects of vaccination on clinical presentation

Background: Previous reports have shown that vaccination rates of adult at-risk populations are low in Turkey. There are differing reports with regards to the effectiveness of the influenza and the pneumococcal polysaccharide vaccine (PPSV23) on the clinical outcomes of community acquired pneumonia (CAP). The purpose of this study was to analyze the influenza (FV) and pneumococcal vaccination (PV) status, the factors that influence the receipt of influenza/pneumococcal vaccine and the effects of prior vaccination on the clinical outcomes in adults hospitalized with CAP. Patients and Methods: Patients hospitalized with CAP between March 2009 and October 2013 and registered at the web-based Turkish Thoracic Society Pneumonia Database (TURCAP) were included in this multicentric, observational study. Of a total of 787 cases, data were analyzed for 466 patients for whom self-reported information on PV and FV was available. Results: In this adult population with CAP, the vaccination rate with both the pneumococcal and influenza vaccines was found to be 6%. Prior FV was found to be the sole variable that was associated with the receipt of PV [OR 17.8, 95% CI (25–75:8.56–37.01), p < 0.001]. Conversely, being vaccinated with PPSV23 was the only predictor of receipt of FV [OR 18.1, 95% CI (25–75:8.75–37.83), p < 0.001]. Compared to the unvaccinated cases, the chest radiograms of the vaccinated patients revealed less consolidation. The latter also reported fatigue, muscle pain and gastrointestinal symptoms less frequently. Although there was a trend for lower 30-day mortality and for lower rates of intensive care unit (ICU) admission, these did not reach statistical significance. A pneumonia severity index (PSI) score ≥ 90, CURB-65 score ≥3 and multilobar involvement, but not the vaccination status, were identified as independent determinants of ICU admission. Conclusions: This study showed that, among patients hospitalized with CAP, the FV and/or PV rates are low. Prior vaccination does not appear to significantly affect the clinical outcomes. © 2017 Taylor & Francis