Budi Prawara

The Influence of Particles Size and Composition Variation of NiCr-CrC(20NiCr) Metal Matrix Composites Coatings Properties on Boiler Tubes Application

Deposition of NiCr-CrC(20NiCr) metal matrix composite (MMCs) coating have been applied on the substrate of boiler tubes material with High Velocity Oxygen Fuel (HVOF) thermal spray method and constant parameter. Variation of particle size and composition on MMCs was conducted to determined the optimum conditions for boiler applications. Microvickers hardness, metallography and thermal shock resistance testing were investigated. The best performance for boiler tubes application is MMC NiCr-CrC(20NiCr) with 270 mesh of NiCr particles size and 60:40 of composition as evidence by the highest of hardness value (410 Hv) and slightly of discoloration after thermal shock resistance with two variation cooling medium. While at MMC NiCr-CrC(20NiCr) with 70:30 variation composition, coating hardness value will decrease in line with the smaller of particle size of NiCr.

Design System of High-Velocity Oxygen Fuel (HVOF) Thermal Spray Coating Based on Computerization

Wear and corrosion are problems prevalent in the industrialized world. One way to overcome this matter is the process of coating with a thermal spray coating. The coating process is categorized into two processes based on the heat source, i.e., combustion and electric. One example of combustion process is the high-velocity oxygen fuel (HVOF). The HVOF system which is operated manually has been studied in previous works. Computerized HVOF system is developed and manufactured in this study to improve reproducibility of coating and safety of operator. ATMega16 microcontroller was connected with several sensors (oxygen mass flow controller, nitrogen mass flow controller, propane mass flow controller, and pressure sensor), and Visual Studio.Net 2013 was used to create a graphic user interface (GUI). Based on test results obtained, it was found that the GUI successfully communicated using serial communications and could access the input/output (I/O) required by the microcontroller. Combinaton of gas mass flow controller and pressure sensors result in precise control of oxy-fuel combustion process.

Analysis of 6-DOF robot trajectory planning for spray coating application based on workpiece orientation using blender open source software

This paper presents an analysis of a 6-DOF robot trajectory planning for spray coating application using Blender open source software based on workpiece orientation. Four common workpiece orientations were chosen to be simulated and analyzed. The four chosen trajectories were taken from the mesh surface of workpiece model with their own corresponding workpiece orientation. Over these predetermined task trajectory and a fixed assigned task time, the iterative changes of the six joint angles were generated using Blender built-in Jacobian inverse kinematic solver. From the obtained real-time data, the six joint angle real time curves with respect to the sampled time were then plotted. The angular velocity and angular acceleration curves were then derived from these joint angle curves. Regarding to all of these curves, the optimal task trajectory was then chosen.

Tow eye failure analysis using energy strain release

The crack initiation of tow eye is doing research on crack propagation. Finite element method simulation used in the tow eye crack growth analysis. This simulation used ANSYS software to study about characteristic during loading time based on load history. The static approach is chosen in this research to purposes failure mode on the tow eye sample. Testing for the material of tow eye to determine the simulation, such as tensile test, and Optical Emission Spectroscopy test to determine the chemical composition of tow eye. On the end of test, noted that tow eye material is manganese steel, the input data from material properties is using with finite element method (FEM) based on fracture mechanic theory. The simulation with ANSYS also using Strain Energy Release (j-Integral) approach to calculate mode shape of failure. The result of simulation gives representation about the contour of crack. Finally, the conclusion of research, FEM method can be the prediction of Stress Intensity Factor and j-Integral in all of contour of crack to determine width of crack.

Development of HVOF Coating of Hydroxy Apatite on Titanium Alloy with Carbon Nano Tube Intermediate Layer

Hydroxyapatite (HA) is considered as convenient material for the coating of titanium alloy in implant aplication. With the purpose to improve the morphology structure of HAP coating, the present research concerns in studying the effect of carbon nanotube (CNT) intermediate layer on HAP coated of titanium alloy. From SEM characterization, it can be observed that both of HAP coated sample, with and without CNT intermediate layer have porous nodular structure a characteristic of thermal spray coating without any micro-crack. However finer and more irregular structure observed on the sample with CNT intermediate layer, which is confirmed from XRD characterization, that lower degree of crystallinity occur on sample with CNT intermediate layer. After the coating, both of the samples were post annealed at 600 and 700°C for one hour. It was observed that micro-crack observed on the sample without CNT intermediate layer after post annealed at 700°C, while the rest of both samples observed without micro-crack.

Thermal Oxidation of NiAl-Al2O3 Coated on Mild Carbon Steel

Thermal oxidation is believed as an important phenomenon that naturally occurs on material subjected to elevated temperature such as NiAl-Al2O3 coated material. In the present study, thermal oxidation on this coated layer was prepared by heating processes of NiAl-Al2O3 coated on mild carbon steel. Deposition of NiAl-Al2O3 was performed by high-velocity oxy fuel (HVOF) process, whereas subsequent heating processes were performed at 3 different temperatures 600oC, 800oC and 1000oC. After the process, the effects of this thermal oxidation process on the phases formation, microstructure and qualitative toughness of thermally sprayed NiAl-Al2O3 coating were investigated. The results showed that significant amount of NiAl-Al2O3 phase was transformed into NiO phase by heating process at temperature higher than 800°C. In addition, decreasing of thickness of the coating layer was also found as the service temperature increases from 800 to 1000oC. Increasing of hardness was also observed as the heating temperature increases, which is predicted due to the formation of excessive oxide on the coating layer that in turn might impart the toughness of this layer. These conditions suggested that a careful determination of service temperature have to be taken in order to avoid excessive oxidation of the coating layer.