Influence of some Chemical Elements on SDAS of A357 Alloy

A solidification model of coarsening coefficient for the criterion of secondary dendrite arm spacing has been established in this paper. When the model is applied to aluminum cast alloy, it is found that the model is in good agreement with the experiment results. Experiments and analysis show that addition of some chemical elements is conducive to the refinement of the secondary dendrite arm spacing under the same solidification condition. Different chemical elements have different refining effects, and Zr and Ti have better refining effect on A357 aluminum cast alloy than Cu.

Effect of Directional Solidification Condition on Interfacial Reaction between DD6 Single Crystal Superalloy and Zirconia-Silica Ceramic Core

The characterization of the interfaces between DD6 single crystal superalloy and zirconia-silica (ZrO2-SiO2) ceramic cores was performed by optical microscope (OM), SEM and EDS analysis in order to study the influence of directional solidification condition on the interfacial reaction. The results showed that there were chemical reactions on interfaces between DD6 melt and ZrO2-SiO2ceramic cores and the main reaction product was Al2O3. The interfacial reaction involved a complex, interdependent system including the oxidation of Al element, the destabilization of calcia stabilization zirconia (CSZ) and the formation of liquid phase with low melting point. The intensity of interfacial reaction increased with the increase of pouring temperature and solidification time, but the number and size of reaction zones could not increase together because of the limited Al content in DD6 alloy.

Controllable Electrostriction of Polyurethane Film

Although their experimental errors can be observed, pure polyurethane (PU) elastomers are one of the most important class of polymers due to some remarkable electromechanical characteristics such as large electric field induced strain, high specific energy and fast speed of response. In order to obtain the large strain at low electric field, a dependence of the solidification condition on strain was investigated for pure polyurethane films. Optimum solidification condition to get thin film with 19 μm thickness remarkably enhanced the strain at high electric field at high electric filed, although they show the low strain at low electric field at low electric filed. The starting point of the convergence occurred at a lower electric field for the solidification condition to get thick film with 150 μm thickness as opposed to for the optimum condition to obtain the thin film with 19 μm thickness. Based on results of crystalline volume fraction and crystalline periodicity, strongly attributed to not only polarization, but also electrostriction, the strain was controlled by the solidification condition. The optimum solidified samples do not have convergence until 20 MV/m. Based on the prediction and experimental results, the electrostriction of PU films depended on its solidification condition.

Influence of Deoxidation Methods on Inclusions in Sub-Rapid Solidified Low Carbon Steel

The size, distribution, content and type of inclusions under Al, Si-Mn, Ti deoxidized conditions in sub-rapid solidified low carbon steel were investigated using VLM, SEM and TEM. Results indicated that after deoxidizing by Al, Si-Mn and Ti, the largest size of inclusions was 7.5μm, 5.6μm and 6.5μm respectively. Large amount of inclusions were tiny and dispersed in the sub-rapid solidification condition. The number of inclusions was 5423 per mm2 and the size was mainly smaller than 4μm in Al deoxidized condition. After deoxidized by Si-Mn and Ti, the number of inclusions was much less than before, with the amount of 1307 per mm2 and 1819 per mm2, respectively, and most of them were smaller than 3μm. Type of inclusions varies with different deoxidizer. The inclusions produced by Al deoxidation were Al2O3 and Fe-O-S. Inclusions were Al2O3, Al-O-Mn-S, Si-O-Mn-S and MnS in Si-Mn deoxidation sample. Inclusions produced by Ti deoxidation were Al2O3, Al-O-Mn-S and Ti-O-Fe-Si-Mn-S.