Effects of flux application and melting parameters in investment casting of pure aluminium by in-situ melting technique

Investment cast aluminium suffers porosity defect attributed to the complex combination of various factors including melt quality, casting process parameter and pouring technique. Even though, melt treatment and controlled of the process parameter have promising result, however turbulence developed during pouring of molten aluminium increasing the formation of porosity as a result of the entrainment of the surface oxide (Al2O3) film known as bifilm. Currently, turbulence free filling system was applied in casting process using tilt casting, bottom filling integrated with low pressure and also in-situ casting or in-situ melting techniques to address the porosity problem. However, in-situ melting technique has not been studied to reduce the porosity of the investment cast aluminium due to the oxidation of the granular aluminium occurs during heating hinders the complete melting of the granules. This research develops a procedure for investment casting of aluminium granules of 99.4% purity by in-situ melting technique. The aluminium granules were filled in ceramic moulds and heated at four different temperatures of 700, 750, 800 and 850oC for 30 and 60 min in a high temperature muffle furnace in ambient. As the heating temperature and duration were increased, the aluminium granules incompletely melt and produced a casting, however the granules agglomerate and replicate the shape of the ceramic mould. The aluminium granules oxidised during heating, encapsulated by a layer of complex oxides composed of stable [α-Al2O3], metastable [γ-Al2O3] and hydroxides. The thickness of the oxide layer formed on the surface of the air-heated granules increased as the heating temperature and duration were increased. The aluminium granules then were heated at the temperature of 850oC for 30 min in argon environment at the flow rate of argon gas 0.5, 2.5 and 5 l/min to reduce the oxidation of the aluminium granules. The thickness of the oxide layer formed on the argon-heated granule (5 l/min) was reduced by 60%, but failed to produce a casting. NaCl-KCl flux was applied, which was mixed and sprinkled on the aluminium granules at the Al:Flux ratio of 1:0.2, 1:0.25 and 1:0.33 and heated at the temperature of 850oC for 30 min to break the oxide layer that encapsulate the granules during heating. At the Al:Flux ratio of 1:0.33, 99% of the aluminium granules were successfully melted and produced a casting. The granules began melting at the temperature range 657.2 to 658.4oC and completely melted in 16 min with final melting temperature between 660.1 and 660.6oC. The average porosity level of the casting was 1.22%, which is lower than the investment cast aluminium produced by current pouring technique (2.48%). The low porosity level was attributed to micro-intergranular porosity present in the casting due to volume shrinkage. Investment casting of aluminium granules by in-situ melting technique with application of NaCl-KCl flux at the Al:Flux ratio of 1:0.33 mixed and sprinkled on the granules heated at the temperature of 850oC for 30 min producing low porosity aluminium casting

Study on characteristics behavior of developing nozzle for aerosol spray

A new generation of aerosol technology are expand rapidly where the research and development are focused on the analysis of propellants, packaging and ingredients to make the aerosol has a high performance product. However, there are a few main problems with pressurised aerosol spray, which are the production of VOC and the quality of spraying process. Therefore, in this study the development of an internal nozzle has been investigated to analyse the characterictics of spray by using CFD simulation. The analysis is focused on various pressure supply up to 9bar, where the n-butane and water are applied as a liquid phases material. The simulation is done based on two types of selected nozzle design. The result shows that, the values of velocity, TKE and Reynolds Number for both liquid phases are increase when the pressure supply increased. It was observed that, when comparing the two type of nozzle design, it shown that the value of velocity and Reynolds number is relatively similar for both liquid phases, while the TKE value is more difference due to the material properties and nozzle design. Therefore, the use of water is acceptable as an alternative to substitute the n-butane liquid phase in producing an aerosol spray product

Penerapan Model Pembelajaran Pakem Dalam Meningkatkan Hasil Belajar Pada Materi Sepak Bola Siswa Kelas Ivb SD Negeri 013 Mekarsari

This study aims to describe learning outcomes through the application of PAKEM learning model. The subjects of the study were the students of grade IVb SD Negeri 013 Mekarsari. Improvement of learning outcomes in terms of four categories, namely the ability to absorb, the effectiveness of learning, mastery of student learning both mastery of individual and classical completeness and mastery of learning outcomes. Instruments used for data collection are oral tests and written tests in the form of LKS conducted after the learning process. The results showed that the percentage of student completeness increased from 19.40% to 55.40% categorized well, the effectiveness of learning is categorized very effective with an average of 88.46%. While the completeness of student learning outcomes expressed. Based on the results of the study, it can be concluded that the application of PAKEM learning model can improve learning outcomes on the material of the students of class IV B grade SD Negeri 013 Mekarsari

BENTUK KALIMAT DAN FUNGSI TINDAK TUTUR EKSPRESIF DALAM NOVEL CRTITICAL ELEVEN

This study aims to describe the form and function of expressive speech acts in Novel Critical Eleven by using expressive speech act theory. The object of this research is the form of expressive speech contained in the novel Critical Eleven and classified by type and function based on the context of the speech. The method in this study used a qualitative descriptive approach with the free-involved-talk (SLBC) technique. The results showed that there were 40 (forty) data regarding expressive speech acts in the novel Critical Eleven. The function of speech acts contained in this novel is a function that is adapted to the context of the ongoing speech, namely the function to express apologies, complain, praise, regret, congratulations, thank you, disappointed, ask, longing, ask for help, attention, request, invites, jokes, hopes, commands, and sympathy

The ANTARA and TEMPO Media’s Framing Strategy Differences in Framing the Omnibus Law Ratification Issue

In this research, the authors compared the framing strategy used by the ANTARA media and TEMPO media for the issue of the ratification of the Omnibus Law on Job Creation. This research was conducted descriptively with comparative qualitative approach. A qualitative document procedure was applied in collecting the data. Fairclough's framework of Critical Discourse Analysis and the framing analysis model by Pan and Kosicki (1993) were combined to analyze the data. The result of the data analysis is presented in the table and the interpretation form. The result shows that TEMPO's framing strategy is more clearly defined, while ANTARA's strategy is less clear. In building a negative or positive representation, TEMPO Media tries to present information supported by many sources. Then, the use of images in TEMPO news supports the truth of information, while the use of images in ANTARA media improves the quality of information sources. The five news stories from ANTARA media selected in this study always use the face image of the selected informant as a source of news information. AbstrakPada penelitian ini, penulis membandingkan strategi pembingkaian yang digunakan media ANTARA dan TEMPO dalam membingkai isu pengesahan Omnibus Law Cipta Kerja. Penelitian ini dilakukan secara deskriptif dengan pendekatan komparatif kualitiatif. Prosedur dokumen kualitatif diterapkan dalam pengumpulan data. Kerangka analisis wacana kritis Fairclough dan model analisis pembingkaian oleh Pan dan Kosicki (1993) digabungkan untuk menganalisis data. Hasil analisis data disajikan dalam bentuk tabel dan interpretasi. Hasil penelitian menunjukkan bahwa strategi pembingkaian TEMPO lebih jelas, sedangkan strategi ANTARA kurang jelas. Dalam membangun representasi negatif atau positif, TEMPO mencoba menghadirkan informasi yang didukung oleh banyak sumber. Kemudian, penggunaan gambar dalam berita TEMPO mendukung kebenaran informasi, sedangkan penggunaan gambar di media ANTARA meningkatkan kualitas sumber informasi. Kelima berita dari media ANTARA yang dipilih dalam penelitian ini selalu menggunakan foto sumber informasi yang terpilih pada berita

STRATEGI KETIDAKSANTUNAN DALAM VIDEO DEBAT PEMILIHAN PRESIDEN TAHUN 2019

The goal of this article is to identify and explain impoliteness strategies in the 2019 presidential election debate and to evaluate the role of impoliteness used in the 2019 presidential debate. Qualitative descriptive is the kind of method that used by the researcher. The data was gathered from four YouTube videos of the 2019 presidential election debates and analyzed using the distributional and identity methods. This study used the theory of impoliteness by Jonathan Culpeper (2005) which withhold politeness, sarcasm or mock politeness, negative impoliteness, positive impoliteness, dan bald on record impoliteness. Based on the research result, it is found negative impoliteness was the most frequent impoliteness strategy, accounting for 43%. The speaker demonstrated his superiority by accusing and condemning the flaws of others in this strategy.Keywords: Impoliteness, Impoliteness Strategies, Debate, Electio

The Trace of Minangkabau-Wise in Malaysian Language

Malaysia is one of the seacoast regions of Minangkabau people. The overseas has started since 15th century. They are scattered in almost all regions of Malaysia. Gombak Selangor Darul Ehsan is one of the locations where they lived. This paper attempts to trace the Minangkabau-wise from a unit of language side, namely phonemes. The tracking is done by comparing the phonemes of Minangkabau language which is used in Bonjol under Pasaman Regency with Minangkabau Language which is used by Minang people especially from Bonjol who were migrated to Gombak, Malaysia. The comparison will obtained the tendency of phoneme behaviour among both of Minangkabau Language used by both community groups. The distinction suggests there has been a change in language. In addition, this paper also describes the factors that cause the changes

An Analysis of Cooperative Principles on Asumsi.co's Interviews on Russia-Ukraine War Issue

Cooperative Principle is one of the pragmatics disciplines that should be known by everyone to conduct effective communication, especially diplomats. This research studied the utterances which were uttered by two Russian diplomats who are actively working at the Russian Embassy in Indonesia, Denis Tetyushin and Lyudmila Vorobyova in their interviews with Asumsi.co. The objectives of this research were to identify the maxims of cooperative principle which are produced by the interviewees in the Asumsi.co interviews, to figure out the types of maxims disobedience which are produced by the interviewees, and to recognise the motives behind the interviewees obeying and disobeying the maxims. This study was conducted with a qualitative approach assisted by a statistical descriptive method to see the distribution of the obedience and disobedience utterances. The result of the research revealed 47 data obey and disobey the maxim of cooperative principles. The most obeyed maxim was the maxim of manner, followed by the maxim of quantity, the maxim of quality, and there was no utterance which followed the maxim of relevance rule