Relationship between Specular Reflectance in Visible Light Range and Surface Roughness in AZ31 Magnesium Alloy Subjected to Acidic Aqueous Solution Treatment

Magnesium alloys are of increasing interest in the medical industry due to their biodegradability properties and better mechanical properties as compared to biodegradable polymers. Fiber laser cutting of AZ31 magnesium alloy tubes was carried out to study the effect of cutting conditions on wall surface roughness and back-wall dross. During the experiments, an argon gas chamber was adapted in order to avoid material reactivity with oxygen and thus better control the part quality. A surface response methodology was applied to identify the significance of pulse overlapping and pulse energy. Our results indicate minimum values of surface roughness (Ra < 0.7 μm) when the spot overlapping is higher than 50%. A back-wall dross range of 0.24% to 0.94% was established. In addition, a reduction in back-wall dross accumulations was obtained after blowing away the dross particles from inside the tube using an argon gas jet, reaching values of 0.21%. Laser cutting experimental models show a quadratic model for back-wall dross related with the interaction of the pulse energy, and a linear model dependent on pulse overlapping factor for surface roughness.

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Formability of AZ31 Magnesium Alloy Sheet in Dry Press Forming Using Diamond-Coated Dies

Volume 4: Design and Manufacturing ◽

10.1115/imece2009-10957 ◽

2009 ◽

Author(s):

S. Tsuda ◽

S. Yoshihara ◽

S. Kataoka

Keyword(s):

Surface Roughness ◽

Magnesium Alloy ◽

Magnesium Alloys ◽

Deep Drawing ◽

Chemical Vapor ◽

Alloy Sheet ◽

Az31 Magnesium Alloy ◽

Specific Strength ◽

Press Forming ◽

Forming Tools

Dry press forming which hasn’t used lubricants in the process is the attractive forming technique of zero emission for the lubricants. As one of the dry press forming techniques, the usage of dies coated with a chemical vapor deposition (CVD) diamond film, which are expected to be applied to forming tools owing to their high tribological properties, abrasion resistance and heat resistance, has been proposed. Magnesium alloys have attracted attention owing to their advantages over what such as, high specific strength and ease of recycling. However, they have intractable characteristics, and it is necessary to perform the forming technique at high temperature and to consider lubrication condition. In this study, diamond-coated dies were used in the deformation of magnesium alloy sheets without lubricants in press forming, and the formability of magnesium alloy and its effect on the surface texture of a formed-cup were investigated. Dry deep-drawing tests and dry ironing tests were carried out to estimate the effect of the diamond-coated dies on the formability of magnesium alloy sheets. Furthermore, the formability obtained using the above-mentioned tests was compared with that obtained in tests using non-lubricant dies with traditional lubricant. AZ31 magnesium alloy sheets (thickness: t0 = 0.5 mm) were deformed at 200 °C in dry deep-drawing tests. From the results, it was found that what can be deformed using diamond-coated dies. Moreover, a 20% reduction in drawing force was confirmed compared with the usage of the traditional lubricant (MoS2). Meanwhile, dry ironing tests were performed under conditions of 10% ironing ratio by a method similar to the dry deep-drawing tests. In general, the ironing process, which is the most difficult step in lubrication in sheet forming, has been enabled by the diamond coating technique. Furthermore, it was observed that the surface roughness of the formed-cup walls using the diamond-coated dies was 0.4 μmRz, and, 1.3 μmRz in case of MoS2. It was confirmed that the application of diamond-coated dies improved the surface roughness of the formed-cup. It produced an improvement in the formability of magnesium alloys compared with the traditional lubrication technique (use of MoS2). It was concluded that the validity of the use of diamond-coated dies became clear.

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Preparation of Fe3+ Doped High-Ordered TiO2 Nanotubes Arrays with Visible Photocatalytic Activities

Nanomaterials ◽

10.3390/nano10112107 ◽

2020 ◽

Vol 10 (11) ◽

pp. 2107

Author(s):

Jin Zhang ◽

Chen Yang ◽

Shijie Li ◽

Yingxue Xi ◽

Changlong Cai ◽

...

Keyword(s):

Aqueous Solution ◽

Visible Light ◽

Tio2 Nanotubes ◽

Degradation Rate ◽

Rutile Phase ◽

Visible Light Range ◽

Crystallization Method ◽

Photocatalytic Activities ◽

Tio2 Ntas ◽

Temperature Water

In this paper, the Fe3+ doped rutile phase TiO2 nanotubes arrays (NTAs) were prepared in a low temperature water-assistant crystallization method. It is noteworthy that the Fe3+ doping hardly hinders either the crystallization of rutile TiO2 NTAs or the highly-ordered nanotubular morphologies. Moreover, Fe3+ did not form other compound impurities, which indicated that Fe3+ substitute Ti4+ into the lattice of TiO2. With the introduction of Fe3+, the light absorption range of TiO2 NTAs extends from the ultraviolet band to the visible light range. Photocatalytic testing results indicate that Fe3+ doped TiO2 NTAs can effectively improve the degradation rate of methyl orange aqueous solution in visible light, and the TiO2 NTAs with 0.2 mol/L Fe3+ doping exhibits the highest photocatalytic degradation efficiency.

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Effect of electromagnetic stirring and solution treatment on microstructure and properties of AZ31 magnesium alloy

Materialwissenschaft und Werkstofftechnik ◽

10.1002/mawe.201800062 ◽

2019 ◽

Vol 50 (4) ◽

pp. 454-461

Author(s):

J.C. Bian ◽

B.Y. Yu ◽

L. Zheng ◽

B. Wang ◽

W.J. Shi ◽

...

Keyword(s):

Magnesium Alloy ◽

Solution Treatment ◽

Electromagnetic Stirring ◽

Az31 Magnesium Alloy ◽

Microstructure And Properties

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Preparation of WOx-TiO2 and the Photocatalytic Activity under Visible Irradiation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.1979 ◽

2007 ◽

Vol 336-338 ◽

pp. 1979-1982 ◽

Cited By ~ 4

Author(s):

Hai Yan Song ◽

Hong Fu Jiang ◽

Xing Qin Liu ◽

Yin Zhu Jiang ◽

Guang Yao Meng

Keyword(s):

Aqueous Solution ◽

Titanium Dioxide ◽

Photocatalytic Activity ◽

Visible Light ◽

Tungsten Oxide ◽

Tungsten Oxides ◽

Tio2 Particles ◽

Visible Light Range ◽

Visible Irradiation ◽

Doped Titanium Dioxide

Nanocrystalline tungsten oxide doped titanium dioxide (WOx-TiO2) powders were prepared by TiCl4 hydrolysis and characterized by XRD, XPS, UV–Vis absorption spectra and TEM. Results showed that WOx not only hindered the growth of TiO2 particles but also greatly increased the transformation temperature (>800 oC) from anatase to rutile during sintering; the dominant fraction of tungsten oxides was non-stoichiometric tungsten oxide (WxOy) with Wn+ (4<n<6), which could easily substitute Ti4+ in the lattice of TiO2. The light absorption band of TiO2 changed from the near UV to the visible light range (2.68 eV in 1.0 %WOx-TiO2) because of the tungsten impurity energy level induced by WxTi1-xO2. The photocatalysis experiments demonstrated that the MB in aqueous solution was successfully degraded within 1h using WOx-TiO2 with an optimal WOx dosage of 1% under visible light irradiation.

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