Cutting tools in agricultural machines have to withstand high wear demands. Longer maintenance cycle intervals of these tools can be achieved using coatings reinforced with hard particles, applied onto tool substrates. This work was done to establish the qualified test procedure to characterize carbide containing spray & fuse coatings for agricultural demands under abrasion and impact. Simulating these field conditions in lab-scale, tests were performed with a standard ASTM G65 dry-sand rubber-wheel tester (3-body abrasion) and a special impeller-tumbler apparatus (combined impact and abrasion wear). The interaction of hardphase content and matrix composition was investigated to assess their response varying impact energy effects. The test procedure described is suited to optimize coatings by combining quantitative mass loss measurement with results of surface profilometry. It is shown, that crucial material criteria of carbide coatings, such as edge stability and wear progress, can be characterized in a way which is able to tailor coatings for targeted wear regimes in agriculture.

In Flexoprinting the acceleration of printing speed is the driving force to use more and more lightweight anilox rollers made out of glass or carbon fibre reinforced materials. On the other hand anilox roll manufacturers are constantly looking for coating materials allowing finer engraved structures and the processing of higher ink volumes at extended cleaning cycles. This paper describes basic trends in Flexoprinting and presents the development of a special carbide coating solution showing characteristic advantages compared to the standard plasma sprayed chromium oxide coating. Moreover the TeroStar-process is being presented as a suitable high velocity spraying process to apply this carbide coating onto fibre-reinforced anilox rolls by fulfilling the quality requirements for the laser engravement.

Sintered protective coatings are a proven technical solution against corrosion and erosion of tubes in biomass- and waste-fired boilers. The main field of application are tubes like superheater tubes or heat exchanger tubes in fluidized-bed installations corrosion endangered by the flue-gas stream. These sintered solutions complete other thermally sprayed coatings in those critical cases, where gas-dense overlays are needed due to corrosive damage. In those cases, where oxidation and erosion dominates, thermal spraying without sintering is remaining as primary solution. The development of Twin coatings out of sintered and non-sintered thermally sprayed alloys is showing a new and interesting alternative for tubes exposed to erosive-corrosive stresses under high temperature conditions.

Fusible Ni-B-Si alloys with a variety of alloy additions (Cr, Mo, Cu etc.) have been in service for many years as fused coatings with moderate corrosion resistance. Both gas- and water-atomised powders have been used with the spray and fuse and with the plasma transferred arc process to produce coatings. As the severity of corrosive industrial environments has increased, for example in waste burning boilers, existing alloys have not provided the desired service performance. This study was undertaken to develop a new family of alloys with improved corrosion resistance without sacrificing usability, wear resistance or cost effectiveness. A range of compositions was prepared and evaluated for deposition characteristic, microstructure, hardness, wear resistance and corrosion resistance in various media. The resulting alloy has an exceptional combination of wear and corrosion resistance in comparison to conventional alloys, when tested under comparable conditions.

Spray and Fuse coatings are ideally suited to boiler environments. The fusing step gives to optimized coatings a uniform chemistry and microstructure, a metallurgical bonding, no through porosity, a low oxide content and no cracking. The relative simplicity of the traditional processing equipment is suited to on-site and automated application including coating repair. Although enjoying considerable success in traditional boilers, their advance into new applications appears restrained by the issue of substrate property modifications during fusing. This paper studies the modification in substrate boiler tube materials (microstructure and mechanical properties) associated with the coating of advanced NiCrBSi alloys. Charpy impact, tensile strength, yield strength, elongation and thermal expansion coefficient testing between 22°C and 450°C are measured. By optimal coating design to a specific substrate, the effect on mechanical property modifications by fusing could be dramatically reduced to allow new and reliable coatings systems to be demonstrated for advanced applications. The future for Spray and Fuse coatings in boilers is discussed.