COATING OF CR3C2-NICR/NICRALY/NICR COMPOSITE POWDER BY USING HVOF THERMAL SPRAY BOILER TUBE

• Main Author: Roesma Wardhana, Hendy
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/55344
• Institution: Institut Teknologi Bandung

In the process of producing steam electricity, water vapor is obtained by burning coal continuously. The high temperature and the long time combustion process have potential to damage the main components of the reactor, such as the boiler tube. The type of damage that often occurs is high temperature erosion. One of the several efforts to prevent erosion can be carried out effectively with the HVOF thermal spray process. However, the coating material must be chosen appropriately in order to be able to protect the boiler tube from the threat of the surrounding environment. Several previous studies have shown that ceramic and metal composite powders are very effective in the protection of boiler tube pipes. However, the research on a mixture of 3 types of Cr3C2-NiCr / NiCrAlY / NiCr powders and the effect of size powders on coating performance has not been investigated. This study aims to find optimal performance in the coating layer, by varying the composition and the size powder coating. The coating process is carried out by using the HVOF thermal spray method and following the spraying parameters The coating results were tested to determine the relationship between macro and micro properties of the material. XRD testing was carried out at powder conditions, coating conditions, and after the thermal cycle conditions. The oxidation resistance test was carried out in the furnace for 1 hour at 700oC with 50 cycles. Metallographic testing was carried out to observe the porosity of the coating, meanwhile the microhardness of the coating was tested by using a Vickers microhardness tester. The erosion phenomenon in each layer was studied using the ANSYS-Fluent software simulation, using the Oka erosion equation approach. The layer composed of 60% Cr3C2-NiCr (< 37 m) + 20% NiCr + 20% NiCrAlY showed the lowest layer porosity and the highest hardness. In the erosion test, the layer of 60% Cr3C2-NiCr (< 37 m) + 20% NiCr + 20% NiCrAlY experienced the lowest erosion rate both at an angle of 30o and 90o. Each layer variation shows a decrease in the rate of erosion after subjected to a thermal cycle process. The coating of 40% Cr3C2-NiCr + 30% NiCr + 30% NiCrAlY has the highest oxidation resistance during the thermal cycling process.