Corrosion performance and morphological analysis of activated zinc phosphate coating formed on steel surface

Purpose The purpose of this paper is to study the effect of different concentrations of pretreatment solution of copper acetate (1, 5 and 10 g/L) on the deposition, growth and protection ability of zinc phosphate coating. Design/methodology/approach Zinc phosphate coatings were deposited on steel surface by immersion method. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to study the morphological evolution and chemical analysis of formed coatings. The electrochemical performance of the coatings was evaluated via potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and immersion test in an aerated 3.5% NaCl solution. Findings The results showed that the activation treatment accelerated the deposition of the phosphate coating and improved its surface coverage. A higher phosphate coating weight (7.35 g/m2) and more compact structure was obtained with pretreatment solution of 1 g/L copper acetate. Electrochemical results revealed that the protection ability of the phosphated substrates was markedly enhanced after the pretreatment, and the best corrosion protection was obtained with a concentration of 1 g/L copper acetate solution. The corrosion current density of phosphated substrate was reduced by 64.9% after activation treatment with 1 g/L copper acetate solution. Originality/value In this investigation, dense, stable and compact zinc phosphate layers with improved corrosion resistance were formed on a carbon steel surface after activation pretreatment with copper acetate solution prior to a phosphating step.

Improvement of Enzymatic Glucose Conversion from Chestnut Shells through Optimization of KOH Pretreatment

Worldwide, about one-third of food produced for human consumption is wasted, which includes byproducts from food processing, with a significant portion of the waste still being landfilled. The aim of this study is to convert chestnut shells (CNSs) from food processing into a valuable resource through bioprocesses. Currently, one of the highest barriers to bioprocess commercialization is low conversion of sugar from biomass, and KOH pretreatment was suggested to improve enzymatic digestibility (ED) of CNS. KOH concentration of 3% (w/w) was determined as a suitable pretreatment solution by a fundamental experiment. The reaction factors including temperature, time and solid/liquid (S/L) ratio were optimized (77.1 g/L CNS loading at 75 °C for 2.8 h) by response surface methodology (RSM). In the statistical model, temperature and time showed a relatively significant effect on the glucan content (GC) and ED, but S/L ratio was not. GC and ED of the untreated CNS were 45.1% and 12.7%, respectively. On the other hand, GC and ED of pretreated CNS were 83.2% and 48.4%, respectively, and which were significantly improved by about 1.8-fold and 3.8-fold compared to the control group. The improved ED through the optimization is expected to contribute to increasing the value of byproducts generated in food processing.

Pulp properties and spent pretreatment solution resulting from reed pulping with a low alkali loading

Using reed (Phragmites australis (Cav.) Trin. ex Steud) as raw material, straw pulp was prepared by low alkali (less than 6%) pretreatment combined with mechanical grinding. The effects of pretreatment times and alkali dosages on pulp properties and pretreatment solution were investigated. The results demonstrated that alkali pretreatment affected FPI beating efficiency, and the beating energy consumption was lowest when pretreated with alkali dosage of 4%. With 5% NaOH pretreatment, the produced handsheets showed excellent properties that exceeded the requirements of food packaging paper and C-class corrugated paper. Moreover, low silicon content (≤1.12 g/L) in the pretreatment liquor had an almost negligible effect relative to alkali recovery. Therefore, this study is important for researchers and industrial representatives seeking to use reed straw as material for pulping.

Study on Chromium-Free Pretreatment Solution of Color Coated Sheet

Based on the inorganic and organic composite pretreatment technology, a new chromium-free pretreatment solution consisting of Ce (NO3)3, N-β (aminoethyl)-γ-aminopropyl trimethoxysilane (KH792) and vinyltrimethoxysilane (KH171) was studied and used to treat galvanized sheet. Corrosion resistance of composite silane films on galvanized sheet surfaces was studied using CuSO4 pitting corrosion test and neutral salt spray test. Experimental results show that the corrosion resistance of composite silane film has improved significantly, compared to single silane film. The optimal condition of chromium-free pretreatment solution is that KH792/KH171 ratio is 4/1(v/v), Ce (NO3)3 content is 0.05%(w/w).

Experimental Study on the Effect of Different Pretreatment Methods on Rubber Concrete Work Performance and Compressive Strength

In untreated, clean water, NaOH solution to clean, CCl4 solution to clean the rubber particles of different pretreatments as the main influencing factors, by 51 rubber concrete block pilot study reached different pretreatment methods on different rubber particle size and dosage of rubber concrete workability and compressive strength were investigated. The results show that: water, NaOH solution, CCl4 pretreatment solution, such as a rubber concrete workability and compressive strength were improved, and the rubber particles larger pretreatment on rubber compressive strength of concrete work to improve performance and more obvious.