Zn-Ni alloy – A probable replacement to Cadmium coating

A brief review on Zn-Ni alloy coating as a probable replacement for cadmium coating.Various aspects including the electrolytes employed, deposition conditions adopted, structure and morphology and corrosion behaviour has been dealt with in this review

Influence of Zirconia Incorporation on the Mechanical and Chemical Properties of Ni-Co Alloys

Abstract Ni-Co-ZrO 2 nano-composites are electrodeposited from sulphamate electrolyte and a comparison is made with Ni-ZrO 2 in terms of structure and properties. The Co content in the coatings is in the range of 10-80wt%. The deposition conditions like current density, pH are optimized in terms of microhardness and amounts of ZrO 2 incorporated. The microhardness studies revealed that the maximum hardness is exhibited by Ni-28Co-2ZrO 2 composite. The FESEM study showed a change in morphology from polyhedral to ridge with increase in Co content from 10 to 80wt%. A change in crystal structure from fcc to hcp is also seen. The effect of annealing treatment in terms of microhardness is studied by subjecting the composite electroforms to 800℃. The Co rich composite exhibited better stability compared to Ni rich composites. Ni-28Co-2ZrO 2 composite exhibited better immersion corrosion resistance while, Ni-ZrO 2 composite displayed better electrochemical corrosion resistance. The wear studies showed that Ni-10Co-2ZrO 2 , Ni-28Co-2ZrO 2 composites showed better resistance. Thus, it is seen that the coatings can be tailored to suit various applications

Highlighting the Compound Risk of COVID-19 and Environmental Pollutants Using Geospatial Technology

The new COVID-19 coronavirus disease has emerged as a global threat and not just to human health but also the global economy. Due to the pandemic, most countries affected have therefore imposed periods of full or partial lockdowns to restrict community transmission. This has had the welcome but unexpected side effect that existing levels of atmospheric pollutants, particularly in cities, have temporarily declined. As found by several authors, air quality can inherently exacerbate the risks linked to respiratory diseases, including COVID-19. In this study, we explore patterns of air pollution for ten of the most affected countries in the world, in the context of the 2020 development of the COVID-19 pandemic. We find that the concentrations of some of the principal atmospheric pollutants were temporarily reduced during the extensive lockdowns in the spring. Secondly, we show that the seasonality of the atmospheric pollutants is not significantly affected by these temporary changes, indicating that observed variations in COVID-19 conditions are likely to be linked to air quality. On this background, we confirm that air pollution may be a good predictor for the local and national severity of COVID-19 infections.The authors acknowledge financial support from the Spanish Government, Grant RTI2018-354 094336-B-I00 (MCIU/AEI/FEDER, UE), the Spanish Carlos III Health Institute, COV 20/01213, and the Basque Government, Grant IT1207-19

Development and certification of chromic acid-free anodizing process for aircraft grade aluminium alloys

21-27Chromic acid (Cr6+) anodization process is widely used for the corrosion protection of aircraft aluminium alloys. Hexavalent chromium being toxic in nature need to be phased out by eco-friendly alternatives. In the present study modified tartaric-sulphuric acid (TSA) process has been developed followed by sealing in permanganate based bath to obtain 4 to 6 µm thick anodic oxide layer on 2024-T3, 6061-T6 and 7075-T6 aluminium alloys. The process was carried out using a pilot scale anodizing plant. The anodized specimens were characterized for visual observation, thickness, adhesion, electrical breakdown voltage, corrosion resistance and tensile behaviour. All the tests were carried out as per MIL-A-8625F specifications. The specimens were also subjected for about 800 hrs to real time corrosion testing, 200 metres away from sea shore at Mandapam Camp, Rameshwaram, India. The performance of the permanganate sealed TSA anodized aluminium alloys are comparable with that of the conventional chromic acid anodized coatings. This chromic acid-free anodization process has been qualified to airworthiness regulating standards by Indian military certification authorities. Efforts are in progress to commercialize this technology for use on aero platforms

Development and certification of chromic acid-free anodizing process for aircraft grade aluminium alloys

Chromic acid (Cr6+) anodization process is widely used for the corrosion protection of aircraft aluminium alloys. Hexavalent chromium being toxic in nature need to be phased out by eco-friendly alternatives. In the present study modified tartaric-sulphuric acid (TSA) process has been developed followed by sealing in permanganate based bath to obtain 4 to 6 µm thick anodic oxide layer on 2024-T3, 6061-T6 and 7075-T6 aluminium alloys. The process was carried out using a pilot scale anodizing plant. The anodized specimens were characterized for visual observation, thickness, adhesion, electrical breakdown voltage, corrosion resistance and tensile behaviour. All the tests were carried out as per MIL-A-8625F specifications. The specimens were also subjected for about 800 hrs to real time corrosion testing, 200 metres away from sea shore at Mandapam Camp, Rameshwaram, India. The performance of the permanganate sealed TSA anodized aluminium alloys are comparable with that of the conventional chromic acid anodized coatings. This chromic acid-free anodization process has been qualified to airworthiness regulating standards by Indian military certification authorities. Efforts are in progress to commercialize this technology for use on aero platforms

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Improving the Hydrophobicity of ZnO by PTFE Incorporation

The objective of the present study is to obtain a zinc oxide- (ZnO-) based superhydrophobic surface in a simple and cost-effective manner. Chemical immersion deposition being simple and economical has been adopted to develop modified ZnO coating on glass substrate. Several modifications of ZnO like treatment with alkanoic acid (stearic acid) and fluoroalkylsilane to tune the surface wettability (hydrophobicity) were attempted. The effect of thermal treatment on the hydrophobic performance was also studied. It was observed that thermal treatment at 70◦C for 16 hrs followed by immersion in stearic acid resulted in high water contact angle (WCA), that is, a superhydrophobic surface. Thus, a modified ZnO superhydrophobic surface involves the consumption of large amount of electrical energy and time. Hence, the alternate involved the incorporation of low surface energy fluoropolymer polytetrafluoroethylene (PTFE) in the ZnO coating. The immersion deposited ZnO-PTFE composite coating on modification with either stearic acid or fluoroalkylsilane resulted in a better superhydrophobic surface. The coatings were characterized using Scanning Electron Microscope (SEM) for the surface morphology. It was found that microstructure of the coating was influenced by the additives employed. A flower-like morphology comprising of needle-like structure arranged in a radialmanner was exhibited by the superhydrophobic coating

Tribo-corrosion behaviour of electrodeposited Nickel based composite coatings

Electrodeposition is one of the most technologically feasible and economically superior techniques for producing metal matrix composite coatings. Particle-reinforced metal matrix composites (MMCs) generally exhibited wide engineering applications due to their enhanced hardness, better wear, and corrosion resistance when compared to pure metal or alloy. In the present study, nickel composite coatings (Ni-SiC, Ni-YSZ, and Ni-ZrO2) were successfully synthesized from nickel sulphamate electrolyte containing ceramic particles like SiC, YSZ and ZrO2 by direct current (DC) plating with the aid of mechanical and magnetic agitation. The effect of magnetic and mechanical agitation on microstructure, mechanical, and tribological properties have been analyzed. It was observed from the studies that mechanical properties obtained by adopting mechanical agitation were better compared to those of the coatings obtained using magnetic agitation. The FESEM studies revealed that in Ni-SiC composite the SiC particles were covered by a film of nickel while, in the oxide reinforced composite coatings the oxide particles were distinctly visible on the surface of coatings. Tribological testing of the composite coatings under dry sliding conditions and under wet conditions (distilled water) was carried out. The tribological studies under dry sliding conditions showed that the wear loss was less for Ni-YSZ coating compared to the other Ni composite coatings. However, in distilled water medium Ni-SiC coating exhibited better wear resistance than the other coatings. The corrosion behaviour was evaluated using polarization and electrochemical impedance studies. The studies showed that oxide particle reinforced Ni composites possess better corrosion resistance due to their lower Icorr when compared with the Ni-SiC coating. Tribo-corrosion studies were carried out to understand the synergistic effect of wear and corrosion on the performance of Ni based composite coatings in 0.5M Na2SO4. Among various composite coatings Ni-YSZ exhibited less material loss thereby showing better tribo-corrosion behavior

Influence of Al2O3 addition on the wear and corrosion behaviour of HVOF sprayed WC-12Co coatings

WC-12Co and 30wt.% of Al2O3 powder mixture was sprayed on EN-24 steel using high velocity oxy fuel (HVOF) method. The chemical, mechanical and tribological performances of WC-12Co and WC-12Co-Al2O3 coatings have been evaluated. XRD analysis clearly showed the presence of WC, Co and Al2O3 peaks in WC-12Co-Al2O3 coating. The FESEM studies showed a homogeneous microstructure with low amount of porosity in WC-12Co-Al2O3 samples as compared to WC-12Co coatings. )A, Rp=406 ) as compared to WC-12Co (Icorr=0.9A, Rp= 2010An improved hardness of 1100 Hv was observed with the addition of Al2O3 content compared to 950 Hv (WC-12 Co). The 3D roughness profiles show a higher roughness of Ra ~ 7.6µm for Al2O3 incorporated coatings when compared to WC-12Co coating (Ra ~ 6.5µm). Dry sliding wear results of WC-12Co-Al2O3 coating exhibited higher wear resistance as compared to WC-12Co coating. This is probably due to low porosity levels and good metallurgical bonding between the EN24 substrate and the coating. Electrochemical impedance spectroscopy (EIS) studies showed better corrosion resistance for WC-12Co-Al2O3 coatings (Icorr=0.1 coating. It is concluded that WC-12Co-Al2O3 coating exhibited better chemical, mechanical and tribological properties compared to WC-12Co coating under identical HVOF coating conditions

Synthesis of fused mullite and its use in multifunctional nickel based composite coating

Fused mullite, a commonly used refractory material has been synthesized and adopted in the present study as reinforcement in the nickel composite coating. The composite has been developed through electrodeposition method. The thermal stability of Ni–mullite composite in terms of microhardness was studied at temperatures up to 800 °C and compared with Ni–SiC, a commercialized wear resistant coating. The microhardness of as deposited electroforms was similar for both Ni–mullite and Ni–SiC composites (400 Hk). A marginal decrease in the microhardness of Ni–mullite occurred at 600 °C while, significant reduction was observed beyond 400 °C for Ni–SiC coating. Thus, the Ni–mullite composite has higher thermal stability compared to Ni–SiC. The tribological studies showed that the wear volume loss for Ni–mullite is 2.38 × 10−5 mm3/m while, of Ni–SiC it is 9.58 × 10−5 mm3/m under identical conditions. The potentiodynamic polarization and electrochemical impedance showed that the corrosion resistance of Ni–mullite composite is better compared to Ni–SiC. Thus, Ni–mullite is a multifunctional coating