Electrochemical Deoxidation of Titanium in Molten MgCl2-HoCl3

A new electrochemical deoxidation method is proposed for Ti, wherein a mixture of magnesium chloride and holmium chloride (MgCl2-HoCl3) is used as a flux. In the new process, Ti and C are used as the cathode and anode, respectively. Mg is deposited on the Ti cathode, which reduces the O in Ti to oxide ions (O2). The activity of the generated O2- (aO2-) in the system was effectively maintained at a low level by the formation of holmium oxychloride (HoOCl) and further decreased by the electrochemical oxidation reaction on the anode. By applying a voltage of 3.0 V between the cathode and anode at 1173 K, Ti was effectively deoxidized to approximately 1000 mass ppm O. Based on the results, in this study, an electrochemical cell, that simultaneously deoxidize Ti scrap or powders and recover HoOCl, is designed.

Development of Method for Direct Deoxidation of Titanium using Mixtures of Magnesium Chloride and Rare-Earth Chlorides

To decrease the cost of Ti sponge, Ti scrap is added during the remelting process to produce an ingot. However, the use of Ti scrap as an additive during this process is limited because Ti scrap is contaminated by oxygen (O) and iron (Fe), which are not removable during the remelting process. Here we introduce a new electrochemical deoxidation process for Ti scrap using a mixture of magnesium chloride (MgCl2) and rare-earth chlorides (RECl3, RE: Y and Ho) as a flux. Ti and carbon were used as the cathode and anode, respectively. Mg is deposited on the Ti cathode and reduces the oxygen in the Ti to oxide ions (O2). The activity of the generated O2” in the system, aQi-, is maintained at a low level through the formation of rare-earth oxy chloride (REOCl), and is further decreased by the formation of carbon oxides on the anode. During this process, the concentration of oxygen in the Ti is effectively decreased to 100 mass ppm in the MgCl2-YCl3 flux at 1,200 K. This new deoxidation method is considered applicable to the recycling process of Ti scrap containing large amounts of oxygen.

Smooth GaAs (110) Surface Fabrication Using the Ga-Assisted Deoxidation Method

We have practiced the Ga-assisted deoxidation method on GaAs(110) surface. When the deposit amount of Ga is suitable, flat GaAs(110) surface without any thermal deoxidation induced pits and excrescent GaAs islands obtained with the Ga-assisted deoxidation method. The obtained results suggested that, 9ML Ga was optimized dose for GaAs(110) surface, which is a little more than GaAs(001) surface indicating a thicker oxide layer of GaAs(110) surface.

Growth of InAs Quantum Wires with Ga-Assisted Deoxidation on Cleaved-Edge GaAs (110) Surface

We have fabricated site-controlled InAs quantum wires (QWRs) on the cleaved surface (110) of AlGaAs/GaAs superlattices (SLs) structures by using Ga-assisted deoxidation method. In the surface of SLs regions, InAs QWRs were nucleated on GaAs in stead of AlGaAs. In the (110) surface without superlattices(SLs) structures, QDs with a large size were obtained, which is considered hard to realize. To understand the different InAs growth phenomena in the regions with and without superlattices structures, we suggest that indium adatoms have an apparent trend to migrate to the SLs area.

Studies concerning the Elimination of Cd and As from Retrievable Sn-Sb- based Antifriction Alloys

The present paper studies the possibility of eliminating As and Cd - known to be carcinogenic elements - from Sn-Sb based antifriction alloys using the method of oxidation- deoxidation of the s melt and the method of evaporation/ vacuum sublimation. The use of oxidation-deoxidation method has resulted in alloys with a residual content of Cd of 0.4- 0.5 % whereas in the case of the evaporation/vacuum sublimation method, this content has fallen below 0.1% (as compared to the initial value of 1.02% ). Both methods allowed an almost complete elimination of As from the smelt. Due to its advantages (a high elimination rate of Cd, an almost total elimination of As, the As and Cd vapor take in through condensation), the elimination/vaccum sublimation method can be recommended for an industrial large scale use.