The Growth Mechanisms of Atomic Layer Deposition: An Overview

In this review, the discussion emphasized on the growth mechanisms of atomic layer deposition which consists of a theoretical model and experimentally growth as well as the measurement testing as evidences. The deposition process description with some testing evidences can be used to facilitate in the effort to understand the basic concept of ALD growth mechanisms. Some metal oxides like Al2O3, HfO2, and TiO2 with these employed precursors are typically used for the detailed illustration during the reaction steps. Although the surface chemistry of ALD process has been well understood, systematic description which combine a theoretical and experimentally growth mechanism is still missing. This paper aims to provide a better understanding of ALD growth mechanisms and surface chemistry which eventually able to contribute on the thin film growth processing

ANALISIS KEGAGALAN PIPA BOILER SUPERHEATER PADA PABRIK KELAPA SAWIT

Terjadi kegagalan pada pipa boiler  superheater dengan material ASTM A213 T12 di sistem pembangkit yang berada di Pabrik kelapa sawit setelah pemakaian selama 4,5 tahun. Pipa boiler yang bekerja pada temperatur 600°Cdan tekanan 80 bar mengalami kerusakan berupa pecah pada bagian tengah dengan indikasi adanya bulging pada bagian tengah sejajar sumbu axis disertai penipisan ketebalan pipa dan hadirnya produk korosi. Investigasi dengan metode analisa kegagalan dilakukan melalui beberapa pemeriksaan dan pengujian merusak untuk mengetahui penyebab kegagalan, yaitu pengamatan visual, pemeriksaan komposisi kimia menggunakan spectroskopi, pengujian kekerasan menggunakan micro vickers tester, dan pengamatan struktur mikro menggunakan optical microsccopy dan scanning electron microscopy (SEM). Adanya unsur krom pada bagian yang mengalami pecah yang jumlahnya di bawah range  sangat mempengaruhi penurunan terhadap ketahanan korosi dan nilai kekerasan. Batas butir dari fasa ferit pada struktur mikro menipis dengan ukuran butir yang membesar sebagai akibat telah mengalami sperodisasi dan dekarburisasi serta korosi sumuran dari pemeriksaan SEM pada kerak produk korosi. Hasil analisis menyatakan bahwa pipa boiler superheater mengalami pecah dari dalam dengan inisiasi penipisan ketebalan sebagai akibat dari korosi sumuran pada dinding dalam pipa, yang menyebabkan pipa boiler superheater mengalami pemanasan berlebih pada kondisi operasi temperatur dan tekanan tinggi, sehingga pipa menerima beban panas berlebih dan terjadi pecah..Kata kunci: pipa boiler superheater, pecah,analisis kegagalan, pemanasan berlebih, korosi sumura

Pengaruh Proses Oksidasi Lapisan Metal Matrix Composite pada Substrat SS316

Material SS316 seringkali digunakan untuk komponen yang bekerja pada temperatur tinggi dengan resiko mengalami oksidasi yang menyebabkan penurunan sifat material dan umur pakai dari komponen. Deposisi Metal Matrix Composite (MMC) NiCr+Cr3C2+Al2O3 dan NiCr+WC12Co+Al2O3 menggunakan metode High Velocity Oxygen Fuel (HVOF) thermal spray coating dengan parameter konstan dilakukan sebagai proses perlakuan pada permukaan SS316 untuk meningkatkan nilai kekerasan dan ketahanan terhadap oksidasi.  Tujuan penelitian ini adalah untuk mengetahui pengaruh proses oksidasi lapisan MMC pada material substrat SS316. Proses oksidasi dilakukan dengan variasi temperatur 500° dan 600°C, penahanan temperatur selama 6 jam, kemudian diteruskan dengan karakterisasi serta perhitungan laju oksidasi. Hasil penelitian menunjukkan spesimen MMC NiCr+Cr3C2+Al2O3 yang dilakukan proses oksidasi pada suhu 500°C memiliki laju oksidasi terendah yaitu 6,67 x 10-7 gram/mm2 jam.

WEAR RESISTANCE OF ABRADABLE-CONDUCTIVE POWDER DEPOSITED BY USING HVOF WITH DIFFERENT SURFACE PREPARATION AND SPRAY DISTANCE

Along with many material failures due to worn steel components, HVOF (High Velocity Oxygen Fuel) coating based abradable material can be solution to overcome this problem. However, abradable-conductive material is still rarely used for coating, therefore it needs investigation to find out the optimum parameters of process. In this work, the surface treatment on substrate was carried out by the different methods such blasting, etching, and blasting-etching to obtain the rough surface. The spraying distance of HVOF process was varied on 20 cm and 30 cm. Blasting-etching are able to achieve the roughest surface of substrate. Meanwhile, the spray distance of 20 cm produces thicker layer than the longer spray distance. The combination of blasting-etching and the shorter spray distance are able to reach the optimum wear resistance as presented in pin-on-disc test

First-rate manufacturing process of primary air fan (PAF) coal power plant in Indonesia using laser powder bed fusion (LPBF) technology

Additive Manufacturing technology can now speed up and improve the accuracy of the manufacturing process. Manufacturing products with 3D Metal printing gets simpler, quicker, and more precise. Recent studies showed that 3D metal printing with the type laser powder bed fusion (LPBF) could produce primary air fans (PAF) for industrial applications with a quality that can be compared with the existing model. LPBF manufacturing process showed errorless and had advantages compared with the traditional process, allowing the development of precise 3D shapes and sizes. The penetration tests with visual inspection revealed that the 3D printed product has no surface defects. The surface roughness test showed that the specimen has a slightly more refined surface than the original product. The chemical test showed that 3D metal printing materials resemble original model materials, with Aluminium 89.6% wt. and Silicon 9.57% wt., while other elements are less than 1%. The average hardness of 3D material metal printing is 91.6 HV, while the original model material is 106.03 HV. Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) tests indicate that the oxide that forms is Al2O3

Bi-fluid cooling effect on electrical characteristics of flexible photovoltaic panel

A photovoltaic (PV) system integrated with a bi-fluid cooling mechanism, which is known as photovoltaic thermal (PVT) system, was investigated. The electrical characteristics of flexible solar panel were evaluated for PV and PV with bi-fluid (air and water) cooling system. The integration of monocrystalline flexible solar panel into both systems was tested under a fixed solar radiation of 800 W/m2. A total of 0.04–0.10 kg/s of air flow was utilised in PV with cooling system with a fixed water mass flow rate of 0.025 kg/s. The efficiencies of flexible panel for PV and PV with cooling system were explored. For PV with bi-fluid flow, the highest obtained efficiency of module was 15.95% when 0.08 kg/s of air and 0.025 kg/s of water were allowed to flow through the cooling system. Compared with PV without cooling mechanism, the highest efficiency of module was 13.35% under same solar radiation. Current–voltage and power graphs were also plotted to present the electrical characteristics (current, voltage and power) generated by both systems