Hilmi, Mustofa (2018) Analisis Struktur Mikro, Nilai Kekerasan dan Ketahanan Oksidasi Campuran NiCrBSi-40SiC, NiCrBSi-40WC-Co dan Cr3C2-20NiCr Pada Proses Pelapisan HVOF. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Komponen water wall tube yang terdapat pada boiler tipe circulating fluidized bed (CFB) bekerja pada temperatur sangat tinggi (800–900oC) dan beroperasi pada lingkungan yang abrasive. Kondisi kerja tersebut sering mengakibatkan terjadinya degradasi pada komponen water wall tube. Proses degradasi yang sering terjadi diantaranya adalah pengikisan dan oksidasi temperatur tinggi. Salah satu cara yang bisa dilakukan untuk mengatasi permasalahan ini adalah dengan mengaplikasikan pelapisan dengan jenis pelapisan tahan aus dan oksidasi yang memiliki konduktifitas termal yang baik, seperti High Velocity Oxygen Fuel (HVOF) coating dengan menggunakan bahan pelapis berupa carbide–metal (cermet) alloys.
Pada penelitian ini pelapisan dilakukan pada plat baja karbon rendah dengan variasi bahan pelapis berupa NiCrBSi-40SiC, NiCrBSi-40WC-Co dan Cr3C2-20NiCr. Proses pelapisan dilakukan menggunakan peralatan HVOF. Metode pengujian yang digunakan pada penelitian ini adalah pengujian kekerasan mikro, pengamatan struktur mikro dan pengujian siklus termal.
Dari penelitian ini didapatkan hasil bahwa struktur mikro lapisan NiCrBSi-40WC-Co dan NiCrBSi-40SiC memiliki struktur lapisan yang padat dengan sedikit porositas, tidak ada retakan dan mempunyai persebaran karbida yang merata. Sedangkan pada lapisan Cr3C2-20NiCr terdapat banyak porositas yang disebabkan oleh unmelted particle. Kualitas ikatan antara substrate dan lapisan pada interface dari ketiga spesimen terlihat bagus. Nilai kekerasan mikro tertinggi sebesar 859 HV didapat pada lapisan NiCrBSi-40WC-Co, hal ini membuktikan bahwa penggunaan karbida tungsten (WC) memberikan pengaruh yang signifikan terhadap nilai kekerasan lapisan. Proses pelapisan pada material mampu mengurangi laju oksidasi temperatur tinggi jika dibandingkan dengan material tanpa pelapisan.
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The water wall tube of a circulating fluidized bed (CFB) boiler works at very high temperatures (800-900oC) and operates in an abrasive environment. Such working conditions often result in degradation of the water wall tube. Degradation processes that often occur include the erosion and high temperature oxidation. One way to cope with this problem is by using thin wear and oxidation resistant coatings with good thermal conductivities, such as High Velocity Oxygen Fuel (HVOF) coating using cermet (carbide–metal) alloys.
In this research, low carbon steel was used as substrate with a variety of feedstock materials such as NiCrBSi-40SiC, NiCrBSi-40WC-Co and Cr3C2-20NiCr. The coating process was carried out using HVOF equipment. Micro-hardness test, microstructure observation and thermocyclic oxidation tests are the testing method used in this research.
The result of this research has shown that the typical cross-sectional microstructures of the HVOF-sprayed NiCrBSi-40WC-Co and NiCrBSi-40SiC has dense structure with low porosity, crack-free and has uniform carbide. While in Cr3C2-20NiCr there are many porosity caused by unmelted particle. Adherence between substrate and coating in all specimen seems to be good with a low presence of either cracks or voids in the interface. Maximum value of about 859 HV was obtained from the coating NiCrBSi-40WC-Co, it proves that the use of tungsten carbide (WC) had a significant effect on the coating hardness. The application of coating process on the material is capable of reducing the high temperature oxidation rate when compared to the material without coating.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Additional Information: | RSM 667.9 Hil a-1 3100018074577 |
| Uncontrolled Keywords: | HVOF coating, cermet, high temperature oxidation, NiCrBSi-40SiC, NiCrBSi-40WC-Co, Cr3C2-20NiCr. |
| Subjects: | T Technology > TA Engineering (General). Civil engineering (General) > TA491 Metal coating. T Technology > TN Mining engineering. Metallurgy > TN23 Metal cladding. |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | Mustofa Hilmi |
| Date Deposited: | 14 Apr 2020 08:45 |
| Last Modified: | 14 Apr 2020 08:45 |
| URI: | http://repository.its.ac.id/id/eprint/50625 |
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