No abstract

The high strength low alloy (HSLA) steel used as a large crude oil storage tank (LCOST) was often welded by vertical electro-gas welding (VEGW) and submerged arc welding (SAW). The VEGW specimen was produced by single-pass weld with high heat input (about 100KJ/cm), and the SAW specimen was manufactured by mutil-pass weld with low heat input (about 30KJ/cm). The corrosion behaviors of both samples were studied by electrochemical techniques and surface methods. The research results achieved in this investigation disclosed that the welding process played an important role in obtaining satisfactory corrosion property. In comparison with the SAW joint, the VEGW joint showed uniform microstructure and coarse micro-phase. The scanning vibrating electrode technique (SVET) results demonstrated that the corrosion of the VEGW joint majorly took in the heat effect zone (HAZ) and the attack for the SAW joint mainly occurred in the fusion zone (FZ). In addition, the scanning electron microscopy (SEM) results exhibited that the VEGW joint exhibited a light local attack and the SAW joint demonstrated a © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 heavy uniform corrosion.The electrochemical results showed that the VEGW joint showed lower corrosion rate than the SAW joint. In summary, it can be discovered that the corrosion rates of welded specimens were associated with the welding-pass and the corrosion forms of welded specimens were related to the heat input energy.

No abstract

In this study, β-PbO 2-Co 3 O 4 composite coatings were synthesized on a substrate using the electrodeposition method in an electrolyte containing Pb 2+ and Co 3 O 4 particles. The preparation process study shows that the β-PbO 2 bath containing Co 3 O 4 particles becomes more stable for an ultrasonic dispersion time within 30 min, with the stability beginning to decrease after the ultrasonic time exceeds 30 min. Co 3 O 4 particles in the β-PbO 2 bath are positively charged, with anions being adsorbed onto the particles. The nucleation behavior study shows that the electric field force plays a dominant role in the adsorption process for the Co 3 O 4 particles. The nucleation and growth of β-PbO 2 on the Co 3 O 4 particles started for the particles closer to the substrate. In addition, the thickness of the β-PbO 2 layer on the Co 3 O 4 particles was inversely proportional to the distance between the Co 3 O 4 particles and the substrate. Compared to the pure PbO 2 electrode, the oxygen evolution overpotentials for the β-PbO 2-Co 3 O 4 electrode are decreased significantly, which demonstrates an energy-saving effect.

For Chinese high-fired glazed ceramics, a slip can improve the quality of products in many ways; however, when and how the artisans started applying a slip before glazing is still relatively unknown. Some Han dynasty Jiangdong-type calcium glazed wares were unearthed from two tomb groups in Zhejiang. The results show that under the calcium glaze layer, there is another slip coating, which contains high levels of iron and potassium. The underglaze coating can beautify the wares and it could be regarded as the earliest engobe technology on high-fired ceramic. Further, the raw materials used in the slip coating can be traced back to the so-called mud glaze black pottery, which began to appear in the late Neolithic period. We believe that the high-temperature calcium glaze was made of plant ash, which suggests similarities to proto-porcelain that dates back to the pre-Qin period. These glazed wares might be a typical kind of proto-porcelain from the end of the Warring States period and Han dynasty, representing a combination of mud glaze and plant ash glaze.