The industrial set of PPAW-cladding has gained a higher importance in the last few years. The process is characterised by high quality layers of about 1-2 mm with a low dilution of about 5 % and without intermediate layers. The great amount of different alloys, which can be processed as powders, opens a wide range for industrial applications. Manually PTA-cladding can be performed in different working positions. Presently the full mechanised PTA-cladding process is carried out in horizontal position. Thus the components have to be moved relative to the plasma arc. In order to improve operating efficiency and flexibility when processing wear and corrosion resistant coatings it is necessary to enlarge the working area and to set strategies for cladding in constrain position. The effect of the gravitation force leads in this case to a very difficult governing of the pool, which flows downwards and affects the quality of the coating. Basic knowledge of the mechanised process depending on the cladding position, for example with industrial robots, is not available at the moment, even if this is necessary when cladding huge heavy components. The present work shows coating strategies as well as the influence of process parameters while cladding steel with corrosion and wear resistant powders in constrain position (bottom-up and top-down). Investigations with Ni- and Co-based alloys were examined and the suitability for constrain position was evaluated. Through an optimisation of the heat input it was possible to influence positively the melt flow and to carry out successfully coatings. Finally the transferability was successfully proven on a complex three dimensional component.

A numerical method and software were developed to predict non-stationary conjugated conductive heat transfer, melting and possible evaporation of materials under high energy fluxes impinging onto solid body surface (plasma jet, arc spot, laser or electron beam), and also subsequent cooling and solidification of the melted substrate layer. In the numerical procedure, the finite-element method was employed. The processes of interest can have different characteristic time and spatial scales, which in addition can suffer drastic changes at heat flux densities q ?[108 ;1014 ] W/m2. An advanced procedure was developed to enable dynamic adaptive triangulation of domains involved in the current numerical solution and characterizing the different phase states (liquid or solid) of the materials. This procedure, belonging to the class of the frontal algorithms, allows one to break a solution domain into triangles based only on the domain boundaries. The model applications of the developed simulation software are illustrated.

Typically, highly wear resistant PTA materials for mining and mineral processing applications are developed by adding ceramics like tungsten carbide to appropriate matrices. The problem is that failure during abrasion can often occur as a result of preferential wearing of the soft matrix material or crack formation through the highly loaded brittle ceramic phases. In this paper, the development of new highly wear resistant plasma transferred arc (PTAW) iron based alloys will be detailed. In this case, the matrix material itself was found to have excellent abrasion resistance with high hardness obtained in the weld deposits up to Rc 66 from the development of a fine structure consisting of a high volume fraction of complex M23(BC)6 and M7(CB)3 borocarbides phases. The matrix material is found to additionally exhibit high toughness up to 73.3 MPam1/2 due to an effective distribution of fine carbide and boride phases in a ductile dendrites / cells. When adding WC particles to the starting powder and welding, the matrix was found to effectively wet the WC particles forming a strong tough matrix which avoids the typical “pull-out” or cracking found in conventional PTAW hardfacing materials. Specific weight loss measurements were conducted using ASTM G-65 wear testing and will be correlated to the structure achieved during PTAW. Abstract only; no full-text paper available.