Effect of Spray Distance and Powder Feed Rate on Particle Velocity in Cold Spray Processes

Cold spray technology using micron-sized particles to produce coatings is increasingly used for reparative tasks in various industries. In a cold spray setup, the gun is usually connected to a robotic arm to deposit coatings on components with complex geometries. For these components, the standoff distance used in the cold spray process has to be large enough for easy maneuverability of the gun around a small radial feature. However, a small standoff distance is commonly found in most studies, which is thought to prevent a velocity drop of the particles over a larger distance. Here, a study was carried out by measuring the Inconel 625 particle velocity at different spray distances, ranging from 3 to 40 cm. The highest average velocity of 781 m/s was found at a spray distance of 8 cm. Furthermore, a study with varying powder feed rates was also conducted. An increase in the powder feed rate was found to have a minimal effect on the particle velocity. Inconel 625 coatings deposited at the optimum standoff distance (8 cm) were found to have low porosity and high hardness. The results in this study demonstrate that a larger standoff distance can be applied without a significant drop in velocity for cold spray applications requiring high maneuverability.

Nanoindentation as a Method for Determining the Mechanical Properties of Cold Spray Coatings

The paper presents the methodology behind the statistical selection of input parameters using the example of spraying two cold-sprayed coatings. The Ti and Cr3C2-25(Ni20Cr)-Gr coatings were tested. Despite the large difference in the structure of these coatings, nanoindentation studies were carried out focusing on the nano hardness H and elastic modulus E. Based on the four input parameters and two output parameters, a 2-level factorial 2(k-p) experimental design was performed. The conducted analysis showed the significant influence of the spray distance on the H and E values in the case of the Ti coating. The input parameters of the spray distance and the type of carrier gas used turned out to be statistically significant in the case of the cermet coating. Taking into account the statistical analysis, the coatings were sprayed with modified values of the input parameters.

Lapisan Plasma Spray Ni-Al dan Al-Si Pada Tabung Baja Tahan Karat Austenitik Dengan Jarak Semprot Terbatas (Atmospheric Plasma Spray Coating of Ni-Al and Al-Si on Austenitic Stainless-Steel Tube with Limited Short Spray Distance)

Atmospheric Plasma Spray (APS) coating is a widely used thermal spray coating process in industrial applications. High density and high bond strength coating are the main features of this process that is required in almost coating properties for specific applications. The geometrical condition of the workpiece substrate dictates the parameter needed to achieve a certain quality of the coating. Changes in the geometry require modification on the parameter of the process to maintain the quality of the coating. Aluminum Silicon and Nickel Aluminum coating were applied on Stainless Steel substrate casing. Due to the limitation of spray distance between nozzle gun and substrate surface of the casing, modified several parameters of the process were taken. Several parameters were investigated to find out the optimum result of coating and verified with tensile bond strength test, hardness test, and microscopic analysis examination. These activities that involved modification of parameters, mechanical testing, and visual inspection informed that power as a function of voltage and ampere, powder feed rate, the surface speed of substrate (the particular amount of workpiece rotation per minute), and traverse speed of gun, contribute to the result of the optimum coating.

Heat transfer behavior during water spray quenching of 7xxx aluminum alloy plates

The desired microstructure and mechanical properties of heat treatable 7xxx aluminum alloy can be achieved after spray quenching by controlling spray parameters. However, heat transfer behavior between specimen and quenchant is transient and complicated in quenching process. In this paper, a spray quenching system was utilized to quench for 7xxx aluminum alloy. The influence of spray parameters, including spray pressure and spray distance, on heat transfer behavior was examined and discussed. Heat flux and heat transfer coefficient were calculated by iterative method. The results indicated that the aluminum alloy experienced transition boiling, nucleate boiling and convection cooling regimes during spray quenching process. Heat transfer capability firstly increased and then decreased with the increasing of spray pressure or spray distance. A function of local heat transfer coefficient which is variable in specimen surface temperature, spray parameters and spatial location was constructed. Residual stress of 7xxx aluminum alloy plates was increased firstly and then slightly differed with the increase of volumetric flux.

Implementasi Motor Servo MG996r Sebagai Robot Pemegang Batang Nosel Pada Sprayer Elektrik Berbasis Arduino Mega2560

The sprayer is one of the equipments that is often used in agriculture, especially in rice plants to control pests and diseases. The use of the nozzle rod on the electric sprayer still uses hands resulting in the spray distance on the rice being not constant. To answer this problem, the researcher will create an innovative robotic hand holding the nozzle rod on an electric sprayer that will direct the nozzle rod constantly. Servo MG996r as a rectifier of the motion of the nozzle stem which will determine the distance and area of ​​spraying on rice. To achieve maximum dispersion in rice with a 4:1 legowo system with a servo rod length of 50 cm and a spacing between rice of 25 cm, the servo must move forward and backward at an angle of 110° - 180° which can be seen on the LCD and the distance of the nozzle rod on the object can be up and down to 38 cm and up 24 cm from the starting position. The results obtained by the robotic hand holding the nose bridge can work optimally.

Effect of Spray Distance on the Microstructure and High Temperature Oxidation Resistance of Plasma Spray-Physical Vapor Deposition 7YSZ Thermal Barrier Coating

In order to study the effect of spray distance on the structure and high temperature oxidation resistance of feather-columnar thermal barrier coatings, the feather-columnar ZrO2-7wt. % Y2O3 (7YSZ) thermal barrier coatings were prepared at spray distances of 650 mm, 950 mm, 1100 mm, 1250 mm, and 1400 mm by plasma spray-physical vapor deposition (PS-PVD) technology. The surface roughness, micro morphology, and porosity of the sprayed 7YSZ coating were analyzed by 3D surface profiler, SEM, XRD, etc., and the impedance spectrum characteristics of the 7YSZ coating were characterized by electrochemical alternating current (AC) impedance technology. In addition, the high temperature oxidation resistance test of 7YSZ coating under different spray distances was carried out at a temperature of 1000 °C to study the influence of spray distance on the high temperature oxidation resistance of 7YSZ coating. The research results show that the surface roughness and porosity of feather-columnar 7YSZ coating increased sequentially with the increase of spray distance. At the same time, The YSZ grain boundary resistance value increased exponentially as the porosity of the coating increases. Where the spray distance was in the range of 650 mm and 1250 mm, the high temperature oxidation rate constant of the coating increased with the spray distance. However, the spray distance was greater than 1250 mm, and the spray distance had no significant effect on the high temperature oxidation resistance of the coating.

Effect of HVOF spraying parameters on fracture, erosion and thermal properties of Fe alloy-based coating materials

Fe-based coating (Fe50Mo5C15Si10Cr10Ti10) was deposited on 316L stainless steel substrate by high-velocity oxy-fuel spraying coating process. High-velocity oxy-fuel spraying process parameters such as oxygen flow rate and spray distance were varied to investigate their effect on mechanical, wear and thermal properties. The prepared coatings were characterized in terms of mechanical properties such as micro-hardness and fracture toughness, thermal properties and erosion wear properties. X-ray diffraction analysis showed presence of hardened phase Fe2Ti and Fe-Cr. Results of this study indicated that increase in oxygen flow rate from 200 to 250 slpm improved the fracture toughness and micro-hardness by 33% and 6.7%, respectively. On the other hand, increase in spray distance decreased the fracture toughness and micro-hardness by 27.2% and 6.7%, respectively. The wear rate was increased with the increase in oxygen flow rate and decreased with the increase in spray distance. The erosion wear rate was more dependent on fracture toughness as compared to micro-hardness.

Tribological Study of HVOF Sprayed Tungsten Carbide Coated Stainless Steel

Corrosion and Wear, or a combination of both, are the main causes of degradation of metals used in the various industrial sectors. Degradation of the metals can be slowed down by adding a layer of resistant coating on the metal surface. This coating separates the base metal from a corrosive environment, reduces wear, and improves the appearance of the metal. The workpiece after coating becomes a composite that has properties far better than the substrate alone. There are various coating techniques, HVOF is one of the most important and widely used processes to protect the metals from wear, corrosion by providing hard and dense coatings. WC coating done by the high-velocity oxy-fuel (HVOF) spray method is the widely used method for providing a layer of corrosive resistance to a wide range of materials that are used in many different industries. In this study, Tungsten carbide (WC-12CO) Coating, HVOF Spray method was studied in great detail. Tungsten Carbide coating was done on a SUS400 Stainless steel substrate using HVOF Spray Process. An, Experiment was done to analyze the various effect of different parameters namely, oxygen rate, propane (fuel) rate, powder rate, spray distance on hardness, and surface roughness of a SUS 400 Stainless Steel substrate. Process optimization was done by using Taguchi and ANOVA methods. It was found that achieving maximum hardness was greatly dependent on propane (fuel) rate followed by powder rate, spray distance, and oxygen rate. The hardness decreases with the increasing fuel rate. And, achieving minimum surface roughness was greatly dependent on spray distance followed by oxygen rate, propane (fuel) rate, powder rate. Surface Roughness increases with increasing spray distance.