Study on the Effect of Dry–Wet Cycles on Dynamic Mechanical Properties of Sandstone Under Sulfuric Acid Solution

Author(s):  
Xin Huang ◽  
Jianyong Pang ◽  
Jiuqun Zou
e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Jiping Yang ◽  
Philip J Brown

AbstractHollow fibre membranes with more sponge-like morphology and improved gas permeation performance were spun from 20% polyetherketone (PEK) /sulfuric acid (H2SO4) dope solution with aqueous sulfuric acid solution as coagulant using dry-jet wet spinning process. The membrane morphology, mechanical properties and gas separation performance (hydrogen, methane and carbon dioxide) of as-spun PEK hollow fibres have been measured using SEM, Instron and gas test rig. Better cross section structures and mechanical properties in as-spun PEK hollow fibres were observed when aqueous sulfuric acid solution replaced water as coagulant (internal and external). The hydrogen/methane selectivity of up to 40 and hydrogen permeation rate of 3.65 GPU obtained in PEK hollow fibre membranes using 30% sulfuric acid solution as internal and external coagulant simultaneously at the bore fluid injection rate of 30 ml/h are higher than those reported in literatures. Furthermore the effects of bore fluid injection rate and various coagulants on the membrane morphology, mechanical properties and gas separation properties were investigated, as well.


Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1838
Author(s):  
José Cabral-Miramontes ◽  
Facundo Almeraya-Calderón ◽  
Francisco Estupinán López ◽  
María Lara Banda ◽  
Javier Olguín-Coca ◽  
...  

Hard-anodized is a widely used method in the aeronautical sector to improve aluminum alloys abrasion and corrosion resistance. Aim of this work was to characterize the mechanical properties and resistance hard-anodized aluminum 6061 in citric acid solution as a replacement sulfuric acid solution were investigated. Aluminum alloy 6061 was used as the base material to produce the hard anodizing; this process was carried out in a citric and sulfuric acid solution, applying current densities 3 and 4.5 A/cm2 and subsequently exposed to 3.5 wt. % NaCl solution. Microstructure and mechanical properties of the anodizing material were characterized by scanning electron microscopy (SEM) and Vickers microhardness (HV). Corrosion behavior of the hard-anodized material it was carried out with electrochemical techniques as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) respectively. Results obtained indicated that all samples anodized in citric acid solution showed negative hysteresis and lower corrosion current density (1 × 10−10 A/cm2), indicating generalized corrosion on the material surface. EIS results show that anodizing in citric acid solution and a current density of 4.5 A/dm2 provides better corrosion protection than a sulfuric acid solution.


2015 ◽  
Vol 37 (2) ◽  
pp. 162-167
Author(s):  
V.A. Vilensky ◽  
◽  
L.V. Kobrina ◽  
S.V. Riabov ◽  
Y.Y. Kercha ◽  
...  

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