Surface treatments for nickel and nickel-base alloys

Surface treatments of nickel and nickel alloys by diffusion coating, electroplating, explosive hardening, peening, and other method

Preparation And Characterization Of Hydrophobic Polyurethane Coating For Steel Surfaces

Hydrophobic surfaces are repellent to aqueous liquids and corrosive media. Polyurethane (PU) has hydrophobicity which are widely applicable in various fields. In this project, four different coating methods which were drop casting, spin coating, dip coating, and spray coating used to fabricate hydrophobic PU coating films on 304 steel plates. In addition, graphene nanoplatelets (GNP) was added in PU with 0.5% (w/v) to increase the properties of PU coating while stainless-steel 500 mesh was applied on coating surface to create high surface roughness of coating. Then the coatings were characterized through FTIR, XRD, AFM, and WCA measurement as well as mechanical test such as tensile test and corrosion resistance test. The WCA measurement of coating after incorporation of GNP into PU showed the increasement about 12.04°-23.09°. GNP also successfully decreased the corrosion rate of coating in 3.5 % NaCl solution by blocking the corrosive ion from entering the gaps and pores in PU. The mechanical strength of film increased with the existence of strong hydrogen bond within the film. The application of stainless-steel 500 mesh improved the surface roughness of coatings also help in increasing the WCA of 5-8°, air trapped in between coating and surrounding environment protect the coating surface with low surface energy. The application of stainless-steel 500 mesh can further decrease the corrosion rate of 304 steel. This study provides a comprehensive comparison of PU, PU-mesh, PU/GNP, and PU/GNP-mesh coatings surface morphologies, hydrophobicity, and corrosion resistance properties

Thermal Sprayed Coatings Used Against Corrosion and Corrosive Wear

International audienceCoatings have historically been developed to provide protection against corrosion and erosion that is to protect the material from chemical and physical interaction with its environment. Corrosion and wear problems are still of great relevance in a wide range of industrial applications and products as they result in the degradation and eventual failure of components and systems both in the processing and manufacturing industries and in the service life of many components. Various technologies can be used to deposit the appropriate surface protection that can resist under specific conditions. They are usually distinguished by coating thickness: deposition of thin films (below 10 to 20 μm according to authors) and deposition of thick films. The latter, mostly produced at atmospheric pressure have a thickness over 30 μm, up to several millimeters and are used when the functional performance and life of component depend on the protective layer thickness. Both coating technology can also be divided into two distinct categories: "wet" and " dry " coating methods, the crucial difference being the medium in which the deposited material is processed. The former group mainly involves electroplating, electroless plating and hot-dip galvanizing while the second includes, among others methods, vapor deposition, thermal spray techniques, brazing, or weld overlays. This chapter deals with coatings deposited by thermal spraying. It is defined by Hermanek (2001) as follows , "Thermal spraying comprises a group of coating processes in which finely divided metallic or non-metallic materials are deposited in a molten or semi-molten condition to form a coating". The processes comprise: direct current (d.c.) arcs or radio frequency (r.f.) discharges-generated plasmas, plasma transferred arcs (PTA), wire arcs, flames, high velocity oxy-fuel flames (HVOF), high velocity air-fuel flames (HVAF), detonation guns (D-gun). Another spray technology has emerged recently ; it is called cold gas-dynamic spray technology, or Cold Spray (CS). It is not really a thermal spray technology as the high energy gas flow is produced by a compressed relatively cold gas (T < 800°C) expanding in a nozzle and will not be included in this presentation

Research and development program on magnetic electrical conductor, electrical insulation, and bore seal materials - Electrical conductor and electrical insulation materials topical report

Electrical, mechanical, and thermo-physical properties of conductor and insulation materials for application to advanced space electric power system

Building Urban Resilience in the MENA Region‘The context of Climate Change, Conflict and Displacement’

It might seem plausible to argue that the national monitoring of disaster data loss can help countries achieve progress in reporting to the 2015-2030 Global Agendas of the Sendai Framework for Disaster Risk Reduction (SFDRR), the Climate Change (CC) Agreement, the Sustainable Development Goals (SDGs) and the Habitat III New Urban Agenda. Nevertheless, with the lack of climate security protracted displacement data monitoring in the MENA Region, Arab states fragile contexts of urban disaster, urban conflict and urban poverty, can exacerbate the exclusion of internally displaced persons (IDPs) and refugees from disaster resilience assessments, which remains an obstacle in achieving the global targets at the local level. With the weakness of Disaster Risk Reduction (DRR) governance at the local level, the urgency of this study comes from the assigned timeframe to achieve the SFDRR Target (E) to ‘substantially increase the number of countries with national and local disaster risk reduction strategies by 2020’. Accordingly, this research aims to develop a policy guidance that supports DRR decision-makers in developing ‘Urban Resilience Action Plans’ (U-RAP) in fragile settings, using the SFDRR Disaster Resilience Scorecard ‘New Ten Essentials’ in the Middle East and North Africa Region (MENA) - Arab States. In addressing this aim, the researcher recognises the need to re-shape a regional understanding of resilience concept, accompanied by embedding sustainability principles and profiling of DRR regional policies beyond the internationally standardised terminologies, U-RAP Policy Guidance will provide effective means of translating resilience assessment indicators into sustainable actions in fragile contexts. As urban resilience action plans are increasingly reliant on the voluntary effort and ownership of DRR states’ official bodies, and affected with their organisational structures, it is important to identify the key parameters for understanding risk and assessing resilience in fragile settings from the perspective of DRR key stakeholders most vulnerable groups. This will help develop inclusive operational programs for their engagement in resilience decision making process, and form legislative policy guidelines beyond the theoretically bounded disaster resilience indicators and numerically generated indexes. In this study, evidence from secondary data (published and unpublished studies collected from the public domain and organisational reports) provided an overview of the scale and scope of humanitarian crisis and vulnerability to disasters risks in the MENA. A mixed methodological approach for primary data collection was adopted to develop original scientific based evidence, collected by the researcher from first-hand sources and helped recognise the significance of monitoring ‘Climate Security Displaced’ (CSD) people protracted displacement. Using qualitative and quantitative research methods, the correlation between the indicators of the SFDRR New Ten Essentials and ‘human security’ components of IDPs and refugees was identified, shedding the light on the challenges and opportunities for building resilience in the Arab States, and framed the structure for the U-RAP Policy Guidance. Qualitative exploratory data collection methods were applied through focus group discussions and 42 Interviews with key informative experts and DRR key stakeholders, supporting evidence on their role and level of engagement in measuring and building urban resilience. This was followed by examining two case studies of Khartoum-Sudan and Tripoli-Lebanon to generalise results for the Arab States regional context. Quantitative data was collected from a total of 120 questionnaire survey respondents, associating interlinkages between the U-RAP components and societal resilience domains for CSD people at the local level, and feeding into disaster data losses at the national level. This study formed a set of recommendations for Open Data utilisation to fill the gaps in existing resilience assessment data resourcing, monitoring disaster and conflict displacement patterns, inform resilience decision making process for displacement ‘durable solutions’ and guide financing priorities for DRR governance at the local level. The study concludes that international frameworks and resilience assessment tools overlook the sub-regional challenges that are historically witnessed in the Arab States and similar fragile settings globally, which requires a bottom-up costum based innovative mechanisms to enhance national governments commitments to the 2015-2030 Global Agendas. Similarly, there is a need to overhaul current resilience assessment tools and global framework reporting mechanisms into Arab cities' local context of fragility, to improve the accuracy, transparency and validity of the data required to structure effective and efficient disaster resilience action plans ‘leaving no one behind’. As a result, the U-RAP policy guidance has been developed as the main contribution of this study, providing a step-to-step pathway to help decision makers enhance societal resilience, while complementing the matrix of disaster data loss with human security and conflict displacement in the MENA region fragile settings, and guiding similar future research development approaches that can be adapted into fragile settings worldwide

Volume 62 - Issue 3 - December, 1950

https://scholar.rose-hulman.edu/technic/1127/thumbnail.jp

Nano-structured polymer-glass hybrid coatings

The increased attention received by polymer nanocomposites in recent years, has opened the way to research on nanostructured glass polymer hybrids for coating applications. Using polyamide 11 and adding fillers (in this case glass) at the nanometre length scale can lead to innovative modifications to the polymer matrix, giving rise to new structures and properties. This could develop new materials with enhanced properties and may enlarge the coating market to other application areas. Some of the main obstacles to overcome are the control of glass particle size to obtain suitable dispersions on the nanoscale with interaction between components. Nanoscale structures require the development of optimal hybrid precursors. Finding a way to develop the hybrids using melt compounding methods like extrusion, particle size processes and coating techniques have been investigated in this research. The nanostructured hybrids are made using macroscopic fillers, which avoids problems with current regulations on ultra-fine particles. Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy indicate the glass structure during synthesis of tin fluoride phosphate glass was pyrophosphate, mainly built up from phosphate tetrahedral units with one bridging oxygens present within a particular phosphate tetrahedron Qଵ end groups with a low concentration of phosphate tetrahedral units with two bridging oxygens Qଶ polymeric chains. However, sub-optimal melting produced significantly higher concentrations of phosphate tetrahedral units with no bridging oxygens present within a particular phosphate tetrahedron Q଴ orthophosphate structural units. The variations in NH and P − OH vibrations in the spectra revealed that a critical time and temperature of melting were necessary for the conversion of NHସHଶPOସ to produce sufficient PଶOହ for glass forming. During melting, PଶOହ and SnFଶ formed a low-temperature melt, which facilitated melting of the SnO and promoted the formation of a more stable glass structure. The fluorine breaks the P − O − P bonds and induces depolymerisation. The density of the glass reached a maximum at 450 °C for 25 min driven by the need for conversion of NHସHଶPOସ to PଶOହ and miscibility of SnO in the melt. Inadequate melting times and temperatures gave low glass transition temperature (Tg) values because of weak F − Sn and F − P linkages. Glass stability improved with melting due to increased PଶOହ and SnO miscibility enabling stronger Sn − O − P linkages. The results show that melting conditions during synthesis strongly influence critical glass properties and also provide an understanding of optimum processing necessary for future industrial scale-up. Novel hybrids of tin fluoride phosphate (TFP) glass (composition of 50% SnFଶ + 20% SnO + 30% PଶOହ) were synthesized with polyamide 11 and their morphology and mechanical properties investigated. Hybridization was achieved by melt blending up to 25 vol% of glass using different compounding conditions (temperature, screw speed and residence time). Scanning electron microscopy (SEM) showed that the morphology was greatly influenced by the extrusion processing temperature and the glass content. Transmission electron microscopy (TEM) studies revealed nanoparticles of 40 nm in size and suggested good compatibility. In order to determine the existence of miscibility between hybrid components, measurement of the loss tangent using a Dynamic Mechanical Analysis (DMA), was carried out. The presence of two transition peaks in the hybrid containing 34 vol% tin fluoride phosphate glass implied an immiscible system showing heterogeneously distributed regions of very different molecular mobilities. Contrary to the plasticizer effect reported in the literature for some polyamide 6 - TFP glass hybrids, the measurements of mechanical properties by DMA showed a reinforcement effect of glass in the polymer. This was reflected by the increase of storage modulus (Εᇱ) at low and high temperatures in hybrids containing 13, 18 and 25 vol% tin fluoride phosphate glasses, achieving the highest modulus at 25 vol%. Tensile testing revealed a pronounced reduction in ductility for high glass contents. Finally, the first TFP- PA11 hybrid coating was developed with enhanced fire resistance and adhesion to the metal. Hardness and abrasion tests using different glass Tgs showed an influence of the glass Tg on the final coating application

Optimizing the sintering of Cr2O3-nano powders for HVOF applications

The main focus on the project is tailoring a new ceramic coating material, Cr2O3 with the optimum combination of both good mechanical and corrosion resistance properties. With several combinations with the amount of additive (%YSZ) mixed with the main powder Cr2O3, and applying two different atmospheres (H2 and Ar-6%N2) and a number of sintering temperatures we will achieve a space of possible candidates from where it will be chosen the optimum parameters which ultimate properties will reach the highest values. After applying different conditions in a bunch of twenty samples two tests will be developed. An agglomeration strength test is necessary to obtain breaking points out of compressive tests on nanopowders and a study on grain growth is mandatory to control the enlargement of the powders after sintering. Numeric values of breaking points and over 300 SEM pictures they will all contribute to decide about the best parameters for the coating to complete the most favourable settings to be able to spray effectively Cr2O3 nanopowders with HVOF.Ingeniería Industria

Tungsten Inert Gas (TIG) Assisted TiC-NiCoating on AISI 304 Stainless Steel

Metal components very often lose their functionality through wear by various modes such as abrasion, impact or corrosion. To counteract such problems, and there by to extend the service life, modification of surfaces are frequently done. This surface engineering approach finds application across many sectors namely defense, mining, steel, power, cement, petrochemical sugarcane and food. Generally the base material of the component is selected on the ground of strength and cost involved, while the details of the surface properties are adopted for local tribological conditions to which the vulnerable section will be subjected during its service period. There have been wide range advancement in surface engineering technology to square up surface failure in steels. But each technology that evolved has its own limitations. Deposition of thin hard coatings of 0.5 mm can improve tribological properties in terms of low friction and wear resistance. But in case of light metal alloys, when the load is high, the coating may fail by deformation. In such cases reinforcement of metals with ceramics can increase the physical and surface properties like strength, stiffness, wear resistance, high temperature strength and a reduction in weight. Over the years, modification of the matrix close to the surface, as well as reinforcement, has been introduced. The addition of ceramic particles into the molten metal surfaces to form a metal matrix composite (MMC) is a very popular one and is widely used worldwide. The formation of MMC meets the specifications required for specific applications. Tungsten Inert Gas (TIG) welding method produces a small modified hemispherical surface which has a width of few millimeters. It also incorporates less cost compared to laser treatment, so widely in practice. TiC is used as a reinforcement material as it has received some attention being a wear resistance substrate. Ni is used as it is a very good binder that produces a well-mixed Tic-Ni mixture. TIG process was used to melt the TiCNi MMC on an AISI 304 stainless steel. This achieved an approximate micro hardness value of 800HV