Papers by Keyword: Solubility

Abstract: Modified stainless steel grade X45CrNiW 18-9 has been developed through replacement of nickel by nitrogen. The modified steels have been produced in induction furnace under nitrogen pressure and were cast into round ingots with 100 mm diameter. The cast modified stainless steels were forged, followed by air cooling. The nitrogen contents were determined and compared with those calculated using Institute of Metal Science (IMS) equation: The results showed that there are great deviations between the actual nitrogen contents and predicted values through IMS equation. So, an equation has been derived based on chemical composition, pressure and temperature at 1600 °C. [N%] = 0.0078 + 0.0406*X, where X is function of chemical composition and nitrogen pressure. The derived equation has been used to calculate the nitrogen content of different stainless steels using published data. The results reveal the difficulty of deriving a general equation for the prediction of nitrogen content covering different steel compositions. So it is necessary to use narrow composition range. The phases of modified stainless steels have been investigated using Schaeffler diagram, dilatometer and microstructure observations. Both partial and total replacement of nickel using 0.33-0.50% nitrogen, are effective to produce a modified fully austenitic stainless steel grade X45CrNiW 18-9.

Abstract: Niobium is added to carbon steels in small amounts (< 0.1weight %), thus being called a microalloying element, to increase mechanical strength and toughness. When added to steel, niobium is partly soluble in the matrix and another part combines with carbon and nitrogen forming a family of Nb_xC_yN_z precipitates (niobium carbides, nitrides or carbonitrides), where the values ​​of x, y, z depend on the temperature and the chemical composition of the steel. The solubility equations for niobium in austenite available in the literature only provide the niobium content that could be solubilized at a given temperature. But when niobium is added above the solubility limit, the excess niobium will not only form the Nb_xC_yN_z family of precipitates. This is what the proposed model calculates. The proposed model is easy to apply and provided results are very close to those determined experimentally by different researchers, who used different techniques such as atom probe, or matrix dissolution with precipitate filtration, for example. Although the proposed model has been used to calculate niobium in solution in austenite, the same can be applied to any other precipitate, such as carbides, nitrides or carbonitrides of vanadium and titanium, for example.

Abstract: Resin is a compounding ingredient that can be used in tire treads to improve (wet) grip resistance. Increasing tan delta in the temperature range between 0°C and 20°C is important to improve (wet) grip resistance. To understand the behavior of resins and determine which resin is best suitable to improve traction in SBR/BR blends, the solubility of polyterpene and α-methyl styrene resin in SBR-BR blends is investigated. The method for measuring the solubility of resin in SBR/BR blends at a 70/30 weight ratio was developed. The solubility parameters (δ) were calculated based on the group contribution method, and the Δδ values between resins and rubbers were correlated with the weight increase of lightly crosslinked SBR/BR blends at different temperatures. A smaller Δδ means higher solubility of the resin in the rubber, which is confirmed by the high level of resin uptake in the rubber. Based on the research, it was found that molecular weight, polarity, and temperature, are factors, which influence the solubility of resins into the rubber. In addition, based on the DMA measurements, SBR/BR (Ni-cat) containing polyterpene shows a higher tan delta at 0 – 20°C compared to SBR/BR (Nd-cat) containing polyterpene. This fact indicates that a correct selection between the type of rubber and resin is important depending on the requirement needed.

Abstract: Salt is commonly produced from seawater by conventional solar evaporation process in Indonesia. Some of the salt produced has not been able to meet the standard requirement especially for industrial uses and make Indonesia still importing salt. This study aims to develop a precipitation model of various salt components during seasalt production from seawater by varying the brine input and output concentration on the crystallization table using the concept of solubility. The evaporation and precipitation processes during the salt production were modeled using a series of separator and filter units and carried out by making use of the electrolyte wizard in Aspen Plus^®. In this simulation, 9 variation were carried out by varying the brine input at concentration 20 ºBe, 23 ºBe, and 25 ºBe and output at concentration 29 ºBe, 30 ºBe, and 31 ºBe on the crystallization table. It is shown that the purity of NaCl salt is significantly influenced by the the brine input concentration to and the brine output concentration from the crystallization table. The percentage of calcium impurity increases when the brine input concentration to the crystallization table is lower while the percentage of magnesium impurity increases when the brine output concentration from the crystallization table is higher. The percentage of sulfate impurity increases when both the brine input concentration to and the brine output concentration from the crystallization table is lower. In practice, it is advisable that the crystallization in the salt table is carried out from 25 to 29 ºBe to limit the amount of magnesium impurity that can cause salt to taste bitter. Conducting the crystallization in this concentration range would give the purity of NaCl salt of 94.049%, which is in accordance with SNI standard for consumption salt, and the yield of NaCl salt of 78.83%. Further study needs to be done to provide a workable solution on how to make the purity of NaCl salt higher such as by using suitable precipitating agents in the salt production to help the precipitation process of various salt impurities.

Abstract: Using L-octanoyl alanine and L-octanoyl phenylalanine as precursors, they are reacted with magnesium hydroxide to prepare two low-molecular complexes Mg(oct-L-ala)₂ and Mg(oct-L-phe)₂. The composition and structure of the two complexes are characterized by elemental analysis, nuclear magnetic resonance spectroscopy and moisture analyzer, with the solubility and aggregation behavior of the complexes studied. A comparison of the two complexes shows that the Mg(oct-L-ala)₂ complex exhibits better solubility and is easier to aggregate in the mixed solution. In addition, the aggregated solid formed by the aggregation of these two complexes in the solution has optically heterogeneous properties. After further heating and cooling treatment, the Mg(oct-L-phe)₂ complex still retains the optically anisotropic state (liquid crystal state), while the Mg(oct-L-ala)₂ complex forms an optically homogeneous morphology (glass state). This may be affected by the benzene ring functional group in the Mg(oct-L-phe)₂ complex.

Abstract: The chrome alloy has better affinity with nitrogen atom in nitriding process than any other alloy elements in steel. The higher content of chrome element binds larger number of nitrogen atoms. However, the higher concentration of nitrogen atom on the surface of the steel does not often make thicker case depth. This study clarified the phenomenon. The nitriding process was performed in two stages, namely the boost stage in the fluidized bed with the composition of 80 % NH₃ and 20 % of N₂ in 4 hours at 550 °C. Subsequently, the diffusion process was carried out in fluidized bed with the gas composition of 100 % N₂ HP (high purity) in 2 hours. The chemical composition was measured by spectrometry and EDAX. The case depth was identified by micro-Vickers, and metallography was observed by SEM. The concentration of nitrogen atom on the surface of AISI 316 L is twice higher than that on the AISI 4140. The result shows that 0.1 to 1 wt % of nitrogen atom creates diffusion layer, 1 to 5 wt % of nitrogen atom produces nitride layer of γꞌ and ε, and nitrogen atom above 5 wt % forms white layer. The layer strongly depends on the percentage of nitrogen atom concentration. The nitrogen atom concentration is determined by the concentration of chromium element within the steel (AISI 316 L). Meanwhile, the depth of nitrogen atom diffusion is highly determined by the alloy element of Fe (AISI 4140).

Abstract: Telmisartan (TEL), a type of antihypertensive drug, has poor solubility. To improve its solubility, the co-amorphous telmisartan with pimelic acid (PA) in molar ratio of 1:1 and 2:1, respectively, were obtained using a liquid-assisted grinding method. The co-amorphous system was characterized by the powder X-ray diffraction and differential scanning calorimetry. The molecular interactions of the co-amorphous were studied by the infrared spectra. After the formation of co-amorphous, the solubility of TELwas much improved, and the apparent solubility values were approximately 9-15 times as high as that of crystalline TEL. Moreover, the co-amorphous TEL-PA was stored under 25 °C/20% RH for a month without any evidence of conversion by powder X-ray diffraction analysis.

Abstract: Polymeric plastic boxes (named Front Opening Unified Pods (FOUP)) were widely used in semiconductor manufacture to maintain the cleanliness of processed wafer substrates in a controlled mini-environment. Polymeric materials, however, are able to sorb airborne molecular contaminants (AMCs) and subsequently to outgas the sorbed AMCs backward to FOUP’s atmosphere, causing the transfer of AMCs to sensitive stored substrates, named cross-contamination. As a type of AMCs, the NH₃ cross-contamination could cause a severe yield loss to integrated circuits (crystals (haze), resist-development defects (T-topping) or metallic corrosion). Experiments were carried out to establish the NH₃ sorption and desorption kinetics in polyetherimide (PEI), Entegris Barrier Material (EBM)), and EBM/carbon nanotubes (EBMCNT) at NH₃ concentration of 800-ppbv, 21°C, and relative humidity of 40%. The transport coefficients i.e. solubility and diffusivity (D_NH3 and S_NH3) were then determined. The study on NH₃ provides an additional guideline to choose the best raw materials for FOUP formulation in taking into account the potential cross-contamination of AMCs. Numerical simulation model based on obtained solubility and diffusivity values was conducted to demonstrate NH₃ concentration profiles in FOUP walls during contamination and FOUP decontamination, which are inaccessible by conventional experiments.

Abstract: The differential scanning calorimetry and the method of cooling curves are used to obtain data on liquidus temperatures of oxide-chloride systems Gd₂O₃ – K Cl - GdCl₃. The solubility of gadolinium oxide in K Cl - GdCl₃ melts has been studied. This information can be used for a developing process of the reduction of solid rare-earth oxides into their metals in molten salts.

Abstract: Soybean protein isolate (SPI) is widely used in food industry because of its high protein nutritional function and good functional characteristics. However, due to the effect of amino acid composition and spatial structure on natural protein, its practical application is greatly limited. So it needs to be properly modified to meet the needs of production. In this study, SPI was used as substrate to explore the most suitable modification conditions by using complex enzymes (flavor protease, neutral protease, alkaline enzyme and transglutaminase) enzymolysis and then TG enzyme cross linking, in order to obtain SPI products with both solubility and gel as a special protein isolate for surimi products. The results show that: through the single factor experiment and orthogonal experiment, the optimized conditions of gel strength were determined: flavor protease: neutral protease: alkaline enzyme 1:1:2, pH 7, enzymolysis temperature 45°C, enzymolysis time 30 min. The optimized conditions of solubility: flavor protease: neutral protease: alkaline enzyme 1:2:2, pH 7, enzymolysis temperature 55°C, enzymolysis time 60 min. The result of orthogonal experiment: the optimized conditions was that flavor protease: neutral protease: alkaline enzyme 1:1:2, pH 7, enzymolysis temperature 55°C, enzymolysis time 60 min. The gel strength of products was 35.45 g, decreased 5.33% with control; Solubility was 36.24%, increased 54.01% with control. The modified SPI has excellent gel and solubility, and can be further applied to surimi products industry. And the results of this study provide a theoretical basis for its further application in surimi products.