Papers by Author: Fu Xing Gan

Abstract: In China’s freshwater environment, the eutrophication phenomenon has become more and more serious in recent years. The changes of water quality may induce the variation of metal’s corrosion behavior. In this paper, carbon steel as common material of hydraulic structure was the investigated object, and its early corrosion behavior affected by microbes (algae and microbe) in eutrophic lakes was studied using immersion test, electrochemical measurements and infra-red spectrometry techniques. The experimental waters were natural eutrophic water and microbescleaned water. The former was fetched from eutrophic East Lake in Wuhan City, Hubei Province of China, and the preparation of later was making natural eutrophic water sterilized and algae removed by UV radiation. In order to present the changes of carbon steel’s corrosion behavior in natural eutrophic freshwater with and without microbes, comparative experiments were conducted in lab. Both weight loss method and electrochemical techniques showed that, the corrosion rates of carbon steel decreased in early stage for the influence of microbe existence. The analysis of infrared spectra indicated that, corrosion product on the surface of coupons taken from natural eutrophic water, mainly were δ hydroxyl ferric oxide, magnetic iron ore, γ hydroxyl ferric oxide, α hydroxyl ferric oxide and β hydroxyl ferric oxide, with relative concentration ratio of 1:0.314:1.003:0.634: 0.654. While corrosion product on the surface of carbon steel taken from the microbes-cleaned water, mainly were α hydroxyl ferric oxide and γ hydroxyl ferric oxide, with relative concentration ratio of 1:1.215.

Abstract: An ambient-cured organosilicone resin modified with epoxy resin was synthesized with lab-synthesized polysiloxane resin and biphenix-A epoxy resin(E-20) by copolymerization at 180~190 °C for 2~3 hours. The effect of ratios between polysiloxane resin and E-20, reaction temperatures and reaction time on heat resistance and miscibility etc were discussed in detail. The experiment results showed that the epoxy modified organosilicone resin exhibited the best solubility performance and adhesion strength when the ratio of the polysiloxane resin to E-20 was 3:7. The Fourier transform infrared spectra (FTIR) revealed that hydroxy on epoxy resin had reacted with ethyoxyl on organic silicon molecular chain, but no ring-opening reaction happened on epoxy group of E-20. The excellent high-temperature resistance painting, based on these epoxy modified organosilicone resin was prepared with flake aluminum powder as temperature resistance filler, polyamide 650 as curer and WD-50 coupling agent as curing-promoter. It was shown that the temperature resistance was superior to 600°C and the adhesion strength of the coating was up to 1 grade. Scanning electron microscope(SEM) revealed the reaction happened on -Si-O-Si- and Al under high temperature improved the coatings to resist higher temperature. The mechanism of the high-temperature anticorrosion is attributed to “ring-opening reaction” and “cross-link solidification reaction”.

Abstract: Cr-Co-P alloy coating was prepared from trivalent chromium bath and the appearance and performances of the coating were characterized. The Cr-Co-P alloy electroplating bath was prepared through orderly adding cobalt chloride, sodium hypophosphite monohydrate, urea, sodium format, ammonium citrate tribasic, boric acid, and ammonium brome into distilled water. Optimum plating crafts were determined as follows: pH value 1.5~3.0, temperature 25~45°C, plating time 1~15 minutes, and current density 5~25A·cm-2. Reticulate iridium dioxide coating electrode or highly pure graphite electrode were adopted as anode. And electro deposition experiments were carried out with air disturbance. The surfaces of deposited coatings are silvery white, bright and smooth. The Cr-Co-P alloy coatings were characterized by scanning electronic microscope (SEM). The results proved that P is favour to the improvement of deposit corrosion resistance. In addition, Cobalt atoms are in favor of enhancing throwing power and cover power of plating baths. Via adjusting plating bath, the electro-deposition rate could reach at 1.0~1.3μm·min-1, and the contents of P and Co could be controlled in 15~25% and 10~65%.

Abstract: With suitable pretreatment, a compact and even nickel-phosphorus alloy coating was obtained on W-Cu alloy by electroless deposition from solutions containing nickel sulphate as a source of nickel and sodium hypophosphite as the reducing agent and a source of phosphorus. The Ni-P coating was normally prepared from acidic baths at high temperature of the order of 90oC with the pH of 4.8 and it was smooth and uniform and exhibited high crystal refinement and high microhardness and superior corrosion resistance. The microhardness, adhesion and corrosion resistance mechanism of Ni-P deposit were studied. The microhardness of the Ni-P alloy deposit increases greatly by tempering at various temperatures. The Ni-P deposit has a strong adhesive force with W-Cu alloy substrate checked by thermal shock test and scribe test. The anti-corrosion ability of Ni-P coating and its anti-corrosion mechanism were measured using immersion experiment and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Ni-P coating was higher than that of W-Cu alloy substrate in the 10vol.% sulfuric acid, monitoring sweat solution and 3.5wt.% sodium chloride solution. The anti-corrosion mechanism of electroless Ni-P coating immersed in 3.5wt.% sodium chloride solution was studied using potentiodynamic polarization techniques. The surface micromorphological morphology and structure of the Ni-P coating were investigated using Scanning Electronic Microscope (SEM) and X-ray Diffraction (XRD). The results indicated that the Ni-P alloy coating consisted of microcrystals and it was amorphous in structure, and the electrochemical measurement showed passive film formed on Ni-P coating during immersion test in the 3.5wt.% sodium chloride solution.