FENOMENA KEKERASAN, IMPAK, DAN STRUKTUR MIKRO BAJA 0.074 wt.% KARBON PASCA QUENCHING COOLANT

2022 ◽  
Vol 7 (1) ◽  
pp. 35-41
Author(s):  
Basori ◽  
Agung Iswandi
Keyword(s):  
Holding Time

Dalam penelitian ini dilakukan proses pemanasan material baja dengan kadar karbon 0.074 wt. % hingga temperatur 1000 °C. Baja tersebut dilakukan variasi penahanan dalam furnace selama 10, 20 dan 30 menit. Kemudian masing-masing baja yang telah di tahan lalu di quenching dengan media coolant. Setelah dilakukan quenching kemudian diukur nilai kekerasannya dengan alat uji vickers. Setelah selesai uji keras kemudian diuji dengan impak charphy untuk mengetahui nilai penyerapan energinya. Setelah pengujian mekanis semua selesai kemudian dilanjutkan dengan pengamatan foto mikro dengan mikroskop optik. Dari hasil pengujian maupun pengamatan dapat diketahui semakin lama waktu holding time maka kekerasan semakin turun. Selanjutnya, semakin lama waktu holding time maka nilai impak semakin naik. Sehingga dapat diketahui bahwa nilai kekerasan dan impak saling berbanding terbalik dari variasi holding time yang sudah dilakukan. Terakhir, pada pengamatan struktur mikro spesimen, fasa yang terbentuk adalah ferit dan perlit.

scholarly journals Optimization of Sintering Process of Alumina Ceramics Using Response Surface Methodology

2021 ◽  
Vol 13 (12) ◽  
pp. 6739
Author(s):  
Darko Landek ◽  
Lidija Ćurković ◽  
Ivana Gabelica ◽  
Mihone Kerolli Mustafa ◽  
Irena Žmak
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Heating Rate ◽  
Sintering Temperature ◽  
Nonlinear Models ◽  
Slip Casting ◽  
Holding Time ◽  
Alumina Ceramics ◽  
Aqueous Suspensions ◽  
Temperature Heating

In this work, alumina (Al2O3) ceramics were prepared using an environmentally friendly slip casting method. To this end, highly concentrated (70 wt.%) aqueous suspensions of alumina (Al2O3) were prepared with different amounts of the ammonium salt of a polycarboxylic acid, Dolapix CE 64, as an electrosteric dispersant. The stability of highly concentrated Al2O3 aqueous suspensions was monitored by viscosity measurements. Green bodies (ceramics before sintering) were obtained by pouring the stable Al2O3 aqueous suspensions into dry porous plaster molds. The obtained Al2O3 ceramic green bodies were sintered in the electric furnace. Analysis of the effect of three sintering parameters (sintering temperature, heating rate and holding time) on the density of alumina ceramics was performed using the response surface methodology (RSM), based on experimental data obtained according to Box–Behnken experimental design, using the software Design-Expert. From the statistical analysis, linear and nonlinear models with added first-order interaction were developed for prediction and optimization of density-dependent variables: sintering temperature, heating rate and holding time.

scholarly journals A Response Surface Methodology (RSM) Approach for Optimizing the Attenuation of Human IgE-Reactivity to β-Lactoglobulin (β-Lg) by Hydrostatic High Pressure Processing

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1741
Author(s):  
Xin Sun ◽  
Jialing Vivien Chua ◽  
Quynh Anh Le ◽  
Francisco Trujillo ◽  
Mi-Hwa Oh ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Optimal Condition ◽  
Response Surface ◽  
High Pressure Processing ◽  
Molecular Structures ◽  
Holding Time ◽  
P Value ◽  
Molecular Change ◽  
Ige Reactivity ◽  
Β Lactoglobulin

The response surface methodology (RSM) and central composite design (CCD) technique were used to optimize the three key process parameters (i.e., pressure, temperature and holding time) of the high-hydrostatic-pressure (HHP) processing either standalone or combined with moderate thermal processing to modulate molecular structures of β-lactoglobulin (β-Lg) and α-lactalbumin (α-La) with reduced human IgE-reactivity. The RSM model derived for HHP-induced molecular changes of β-Lg determined immunochemically showed that temperature (temp), pressure (p2) and the interaction between temperature and time (t) had statistically significant effects (p < 0.05). The optimal condition defined as minimum (β-Lg specific) IgG-binding derived from the model was 505 MPa at 56 °C with a holding time of 102 min (R2 of 0.81 and p-value of 0.01). The validation carried at the optimal condition and its surrounding region showed that the model to be underestimating the β-Lg structure modification. The molecular change of β-Lg was directly correlated with HHP-induced dimerization in this study, which followed a quadratic equation. The β-Lg dimers also resulted in the undetectable human IgE-binding.

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