Papers by Keyword: DSC

Abstract: In order to solve the problems of wax deposit, this study evaluated the effect of wax cleaning agent used in Changqing and adjusted its formulation. The results showed that the wax removal rate of oil based dewaxing agent was slightly higher than that of emulsion dewaxing agent for crude oil with low salt content. It is possible that the emulsion dewaxing agent contains a certain amount of mutual solvents, which improves its wetting ability at the oil-water interface and makes the oil and water dissolve each other. So that the wax deposit surface from hydrophilic hydrophobic to hydrophilic hydrophobic, forming anti-wax film to prevent wax deposition. Therefore, the wax removal ability of 1#, 3# oil wax is higher than that of oil base wax dewaxing agent.

Abstract: The effect of cold-rolling on mechanical, thermal, and electrical properties as well as microstructure behaviour of the Al-2.93wt.%Mg-0.34wt.%Mn-0.33wt.%Si-0.22wt.%Fe-0.19wt.%Cr-0.24wt.%Sc-0.06wt.%Zr was studied. The material was investigated during step-by-step isochronal annealing in a temperature range from room temperature up to 540 °C and during isothermal annealing at 200, 450 and 550 °C. Precipitation reactions were studied by electrical resistometry, conductivity, (micro) hardness measurements and differential scanning calorimetry. The hardening effect appears due to the additional precipitation of the Al₃Sc and/or Al₃(Sc,Zr) particles. The distinct changes in residual resistivity ratio above ~ 330 °C are probably caused by precipitation of the Mn (,Fe,Cr)-containing particles. This precipitation process is highly influenced by cold rolling but it has a negligible effect on hardness. The apparent activation energy values for additional formation of the Al₃Sc and/or Al₃(Sc,Zr) particles were determined. The kinetics of the Al₃(Sc,Zr)-phase precipitation seems to be independent of Mn-and Mg-addition in the studied alloys. A partial recrystallization of the cold-rolled alloy was registered by electron backscatter diffraction after annealing at 550 °C. The initial difference in microhardness introduced by cold rolling is almost removed after annealing at 550 °C/30 min.

Abstract: In the equilibrium processing methods the system Al-C does not show any solid solubility which means that carbon is not soluble in aluminum. In this work an investigation of mechanical alloying on system Al-C was presented to force the dissolution. Using different techniques such as the X-ray diffraction and scanning electron microscopy (SEM), it was proved the force of dissolution by studying the specters for different milling time and by flowing the evolution during annealing into a DSC. Furthermore, morphology of phases has been studied.

Abstract: The phase transformations of the directionally solidified (DS) and powder metallurgy (PM) Ni-base superalloys were investigated by JMatPro, synchrotron XRD (SXRD) and differential scanning calorimetry (DSC). The minor phases, such as MC, eutectic γ′ and Ni₅Hf, and γ matrix with secondary γ′ existed in as-cast microstructure of DS DZ22. However, only γ matrix was found in PM625 alloy powders. The phase change in both heating (melting) and cooling (solidification) process was investigated by DSC on DZ22 test bar and PM625 alloy powders respectively. The DSC experiment with different heating/cooling rates (5-40°C/min) was performed on DS superalloy DZ22. The results indicated that the heating/cooling rate had obvious effect on the DSC results of the phase transformation temperatures of liquidus, MC carbides, solidus, eutectic (γ+γ′) and secondary γ′. The heating and cooling DSC curves shifted to high and low temperature direction respectively, accompanied by the heating/cooling rate increased. However, the average values of specific peaks of heating and cooling curves are relatively consistent which is close to the equilibrium phase change temperatures of the alloy and makes the results comparable. Besides the average value method, the liquidus temperature of the alloy (0°C/min) can also be obtained by method of linear-fit/extrapolating from 5-40°C/min heating/cooling rates or inflection point deviate from the baseline of DSC cooling curves which could minimize the heating/cooling rate effects. The DSC experiment was carried out on PM625 superalloy powders with different particle size range (0-355μm), the results indicated that the particle size had minor effect on liquidus and solidus temperatures of DSC heating curves, the differences were less than 2°C. The change in phase transformation temperatures under different heating/cooling rate should be considered for selecting the process parameter (heat treatment, HIP or casting) for manufacturing Ni-base superalloy components.

Abstract: This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 μm for a temperature of 750 ° C, for 3.4 and 5 hours. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (1: 1). Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.

Abstract: In order to obtain specific properties in the commercial and engineering applications, PP materials are often combined with additives. Filler is one of solid additive type that made of inorganic materials and is generally distinguished by its influence on the mechanical properties of the resulting mixture with the plastic matrix. Filler dimension less than 100 nm is often categorized as a nanofiller and added to plastics with the range of percentage from 1% up to 10%. Various studies have been conducted to know the influence of filler on mechanical properties, but this study is also conducted to investigate the effect of nanofillers on thermal properties of PP material. Thermal properties are very important to know from the stage of design, processing until the end use final product. Most plastic products are made in soft or liquid condition, the melting temperature (melting temperature, Tm) becomes the basis of the processing parameter adjustment. Investigations done by comparing the thermal properties of commercial copolymer PP material (virgin material and injection molding specimen) and PP materials containing nanofiller (virgin material and injection molding specimen) by using Differential Scanning Calorimetry (DSC), while data of mechanical properties was obtained by the tensile test. Both 1st heating and 2nd heating DSC Experiment showed that nanofilled PP need the highest endothermic effect (2.63 W/g and 1.79 W/g), but nanofiller gave no effect on melting temperature to all type of specimens (in the range of 164.3 – 166.3 °C). The elastic modulus of nanofilled PP was around 1486 Mpa, higher than non-filled PP (999 Mpa).

Abstract: High temperature caused by copper core would have a certain impact on the performance of XLPE insulation during the long running process of the cable. In this paper, the XLPE/PVC cable running for 17years was investigated by using thermal analysis, microstructure analysis, mechanical property analysis and dielectric properties analysis. The influences of long-term operation for the physical and chemical properties of cable insulation are analyzed by the performance of the insulation material. DSC results indicated that position of shoulder peak would characterize the thermal history of material and express the crystal size distribution of XLPE indirectly. Mechanical property test results showed that effect of long term high temperature would decrease the elongation at break and breaking strength of XLPE. SEM results showed that the effect of long term high temperature increased the average size of crystal and the distribution of the crystal became concentrated, meanwhile it verified the relevant conclusion of DSC.

Abstract: Al-based alloys are very preferred for automotive manufacture to produce lightweight vehicles. The positive effect of Sc,Zr-addition on the mechanical properties in Al-based alloys is generally known. Microstructure, mechanical, electrical and thermal properties of the conventionally cast and homogenized Al–Zn–Mg alloy with and without Sc,Zr-addition during isochronal annealing were studied. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared to microstructure development that was observed by optical microscopy and transmission and scanning electron microscopy. It was observed that the Sc,Zr-content in the alloy after casting is not homogeneously distributed but concentrated in randomly localized matrix regions and together with Zn and Mg in the particles at grain boundaries. However, the hardening effect after annealing above 280 °C lightly reflects the Sc,Zr-addition. The distinct changes in resistivity and microhardness as well as in heat flow of the alloys studied are mainly caused by formation/dissolution of the Guinier-Preston zones and subsequent precipitation of the metastable particles from the Al–Zn–Mg system. The eutectic Zn,Mg-containing phase partly disappeared during the annealing above ~ 390 °C. Melting of the Zn,Mg-containing phase was observed at ~ 475 °C. The decomposition sequence of the supersaturated solid solution of the studied alloys is compatible with the decomposition sequence of the Al–Zn–Mg system minimally up to ~ 380 °C.

Abstract: The mechanical, thermal and electrical properties and recrystallization behaviour of the cold-rolled AlMgScZr alloy prepared by powder metallurgy were studied. The materials were investigated during isothermal annealing (400 and 550 °C) and during step-by-step linear annealing from room temperature up to 570 °C. The observed results were compared with microstructure observation by transmission electron microscopy and electron diffraction from a previous study of the Al–Mg-based alloys with Sc and Zr. The precipitation sequence of the Al–Mg system and coarsening of the Sc,Zr-containing particles caused electrical and heat flow changes during the annealing. The presence of the Al₃(Sc,Zr) particles has an anti-recrystallization effect that prevents recrystallization at temperature minimally up to ~ 400 °C. A partial recrystallization of the alloy was registered after annealing at 550 °C already for 30 min. The cause of the anti-recrystallization effect is precipitation of the Mg-containing particles as follows from a comparison to the alloy without Mg. But the Mg-addition to the Al–Sc–Zr alloy prepared by powder metallurgy has a poorer anti-recrystallization effect than a Mn-addition.

Abstract: The objective of this study is to investigate the effect of ionic liquid to PEO-NaCF₃SO₃ solid polymer electrolyte. Sodium ion conducting polymer electrolyte films consisting of Polyethylene oxide (PEO) as a polymer host, Sodium trifluoromethanesulfonate (NaCF₃SO₃) as doping salt and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMiTF) as ionic liquid has been prepared by solution cast technique. Different amounts (5, 10, 15, 20, 25 and 30 wt. %) of EMiTF will be added to the optimized polymer-salt composition to develop PEO - NaCF₃SO₃ – EMiTF polymer electrolyte. Difference Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) indicated that the crystalline degree and the weight loss % of the electrolyte decrease with increasing the wt. % of the EMiTF respectively. The ionic transference number was found in the value of 0.95 which suggests that ions are the charge carriers.