This paper demonstrates the use of two laser cladding automation tools, one that automates laser power and one that automates laser head positioning. Both tools are based on intelligent cameras that evaluate recordings from the cladding zone through the optical path of the laser. The laser power tool monitors and controls local emission from the laser cladding process. The position control tool detects distances between edges on component surfaces and generates an error correction signal based on edge-geometry and material data and various process settings. Examples in which the closed-loop tools are used to clad thin-walled tubes with different alloys and fill irregular grooves on shafts are presented.

Within the scope of a current research project, aluminum bronze alloy wires were arc sprayed at different traverse speeds in order to influence heat transfer and hence the stress state of the coating. Microstructural, chemical, and mechanical analyses were conducted to evaluate adhesive and cohesive properties. The materials used are highly cavitation erosion resistant propeller alloys, CuAl9Ni5Fe4Mn and CuMn13Al8Fe3Ni2. Cavitation erosion tests were carried out and residual stress distribution was measured using a modified hole-drilling method.

This study investigates the cause of process instabilities in large and small scale arc spraying production equipment and in an experimental spray gun. Arc voltage and current, voltage drop at the wire contact sleeves, and wire feed velocity are recorded and spectrum analysis is used to predict the separation of unmelted wire pieces, or cold shots, during spraying with a view to quality assurance. A high-speed camera with pulsed LED illumination is used to observe droplet detachment and spray jet generation. For each case, applied diagnostics are presented and the results are interpreted with respect to the physical causes of instability and how to avoid them.

This paper discusses some of the practical uses of laser cladding and laser fusing in part manufacturing and component repair. It provides an overview of both processes and the types of surfaces they can produce. It presents application examples for each process and interprets corrosion and wear properties of the respective coatings. It also discusses the benefits of repair friendly surfaces.

In this study, different air-cap configurations and shroud designs are developed and tested in twin wire arc spraying (TWAS) trails with the intent of increasing the collision probability of in-flight particles and thereby controlling coating composition and microstructure. In order to obtain greater insight on alloying effects and a better understanding of the coating build-up process, solid nickel and solid iron wires are used as feedstock materials and simultaneously sprayed on medium carbon steel substrates. The effect of polarity reversal and the use of a secondary atomization gas are also assessed. Detailed test results are presented in the paper along with in-depth analysis.

The aim of this study is to determine how various factors, including process parameters and nozzle configurations, affect the shape and size of the spray jet in twin wire arc spraying. In the experiments, steel specimens were sprayed using an iron-based cored wire with a fused tungsten carbide filling. In-flight particle temperature and velocity and fluctuations in voltage and current were measured during spraying. The shape of the thermal spray spot and the 3D footprint of the plume were determined by means of image analysis and tactile surface profiling methods. The results obtained show that spray plume characteristics, and thus particle distribution, are heavily influenced by secondary gas flow, particularly the number, location, and angle of atomization outlet holes in the secondary gas nozzle.

In this study, porous and dense layers of alloy 625 are deposited on nickel foam sheets using a modified twin wire arc spraying process. Sandwich panels with arc-sprayed alloy 625 skins on nickel foam cores were fabricated then subjected to four-point bend testing. The effects of skin porosity on flexural rigidity and overall mechanical behavior are investigated. The ductility of porous alloy 625 skins was improved after heat treatment at 1100 °C for 3 h.

The homogeneity of thermal spray plumes is mostly dependent on the type of feedstock used. Powdery feedstocks, for example, promote homogeneity. If in-flight particles are atomized from a melting bath, however, as in twin wire arc spraying (TWAS), the spray jet is less homogeneous due to the fact that particles are generated by the impingement of an airflow on the melting tips of electrically conducting wires. This work aims to contribute to the understanding of the initiation of such particles in the TWAS process. To that end, cored wires filled with W-rich particles were sprayed, then the process was halted and the wire tips were examined to analyze how the filling powder interacts with the melted part of the velum. 3D tomograms show that the resolidified melt bath is interspersed with spherical and irregular-shaped W-rich particles. The irregular shape implies a partial melting of the W-rich particles.

In this study, FeCrB coatings are deposited by wire arc spraying using powder cored wires to investigate the factors that affect thermal conductivity. Experimental results show that increasing boron content in the wires reduces oxide content in the coatings, which increases thermal conductivity. Annealing also increases thermal conductivity, which can be explained by grain growth and a reduction in porosity.

The introduction of new wire arc spraying equipment with chopped power supplies offers many possibilities to improve the wire arc spraying process. These power sources provide higher process stability even at reduced voltages. On the one hand conventional applications can be enhanced and on the other hand new processes can be developed. Due to the high process stability the introduction of additional particles into the atomizing gas stream is possible. This can be applied to produce coatings with a high wear resistance as well as a high surface roughness. A combined technology of particle injection and the productive wire arc spraying process enables the economic production of innovative functional surfaces. In the last years ITSC, the injection of corundum particles had been presented. In this paper further strategies for inserting particles into the gas stream and experimental results are shown for iron based coatings. For the reinforcement different carbides were injected into the atomizing gas stream.

A ceramic composite coating of a FeB alloy reinforced with cobalt-coated tungsten carbide (WC-12Co) particles and nickel-coated tungsten carbide (WC-12Ni) particles was deposited on a mild steel substrate by arc spraying cored wire, respectively. The microstructure and the worn surfaces of the coatings were analyzed by X-ray diffraction (XRD), Scanning electron microscope (SEM). And wear mechanisms of the coatings have been discussed on the basis of the observation. The results showed that adding WC powders can obviously increase the hardness and abrasive wear resistance property of the coating. The average microhardness of the coatings is about 900~1000 HV 0.1 . In the experimental conditions, the coatings have the excellent abrasive wear resistance which is 7~10 times higher than that of the Q235 mild steel. Plastic microcutting and brittle peeling play the predominant role in abrasion wear of the coating.

A scheme of an oxygen input by particles at Arc Spraying is offered. Both external and internal diffusion processes are taken into account. The oxygen input was separately examined at arc-burning zone and spraying distance. At first the oxygen is dissolved in liquid metal drop up to a limit of saturation. Then slag formation begins accompanied by metal – slag interaction. Modeling of these processes was performed on a base of oxygen input/output mass balance. It was completed by computation of oxygen diffusion flows into gas and metal through interface surface. Mutual influence of alloying elements was also taken into account at slag formation on particle surface. The modeling results are represented in case of arc sprayed steel (1.1 C, 1.9 Mn, 0.8 Si). Propane - air mixture was used as a transporting gas. Good similarity with experiment data was achieved. As shown by calculations, basic share of oxygen input occurs in the arc-burning zone. The investigation results were used in core wire developing and gun designing as well.

Suspension plasma spraying (SPS) is a fairly recent technology that is able to process sub-micrometric-sized feedstock particles and permits the deposition of layers thinner (from 5 to 50 µm) than those resulting from conventional atmospheric plasma spraying (APS). SPS consists in mechanically injecting within the plasma flow a liquid suspension of particles of average diameter varying between 0.02 and 1 µm. Upon penetration within the DC plasma jet, two phenomena occur sequentially: droplet fragmentation and evaporation. Particles are then processed by the plasma flow prior their impact, spreading and solidification upon the surface to be covered. Depending upon the selection of operating parameters, among which plasma power parameters (operating mode, enthalpy, spray distance, etc.), suspension properties (particle size distribution, powder mass percentage, viscosity, etc.), and substrate characteristics (topology, temperature, etc.), different coating architectures can be manufactured, from dense to porous layers. Nevertheless, the coupling between the parameters controlling the coating microstructure and properties are not yet fully identified. The aim of this study is to further understand the influence of parameters controlling the manufacturing mechanisms of SPS alumina coatings, in particular the spray patterns influence.