Showing papers in "Materials protection in 2013"

Research Progress of Encapsulation of Aluminum Nanoparticles

Abstract: The latest research progress of encapsulation technology of Al nanoparticles is reviewed in relation to in-situ encapsulation and surface passivation-encapsulation.The four kinds of encapsulation mechanism of Al nanoparticles are summarized.The similarities and differences between in-situ encapsulation and surface passivation-encapsulation are compared,and the domestic achievements of encapsulation technology of Al nanoparticles are analyzed.It is pointed out that encapsulation-modification of Al nanoparticles is important in preventing Al nanoparticles form.Moreover,suggestions are given about existing problems and development trend of encapsulation technology of Al nanoparticles.

Establishment of Environmentally Acceptable Room-Temperature Phosphating Process and Evaluation of Corrosion Resistance of Phosphating Coating

Abstract: A kind of room-temperature phosphating solution without Ni and nitrites was prepared. The phosphating parameters were optimized based on single factor test and orthogonal test, and the effect of phosphating solution composition on the corrosion resistance of phosphating coating was investigated. It was found that the phosphating solution with optimal composition consisted of 20 g/L zinc oxide, 34 mL/L phosphoric acid, 22 g/L zinc dihydrogen phosphate, 0.45 g/L citric acid, 0.19 g/L sodium fluoride, 0.21 g/L sodium molybdate, 0.35 g/L meta-nitro benzene sulfonic acid sodium and 0.17 g/L sodium chlorate. Besides, the optimized phosphating parameters were suggested as pH value of 2.5~3.5, temperature of 23~30 ℃, and phosphating time of 13~17 min (it could be reduced to 3~5 min when spray phosphating was applied). The phosphating coating prepared under the optimized phosphating parameters had uniform and compact appearance and was free of defects such as rust and adhered dust, while it possessed good corrosion resistance (its mass was 1.2 g/m2; and it was able to endure dripping of copper sulfate solution for up to 57 s and endure immersion in NaCl solution for up to 26 d).

Corrosion Process of Micro-Arc Oxidation Coating of Magnesium Alloy in Sodium Chloride Solution

Abstract: The potentiodynamic polarization curves of micro arc oxidation( MAO) coating of AZ91D magnesium alloys in 3. 5% NaCl solution were measured. The morphology and phase composition of the corroded products were analyzed by scanning ewlectron microscopy and X-ray diffraction,and the corrosion model was established. Furthermore,the corrosion process,corrosion features,and failure mechanism of the MAO coating were discussed. Results showed that,at the initial stage of corrosion, the MAO coating acted as a mechanical barrier to protect the Mg alloy substrate. At the medium stage of corrosion,the corroded products and the MAO coating jointly acted as barriers to protect Mg alloy substrate,and hence improved protective effect was accquired. At the late stage of corrosion,micro-cracks were expanded horizontally and verticallt,and the MAO coating was cut into small particles and peeled off. As a result,localized corrosion pits were generated on Mg alloy substrae,and the protective effect of the MAO coating for magnesium alloys substrate was gradually lost.

Application of Advanced Composites in Unmanned Aerial Vehicle and Solar Powered Airplane

Abstract: Advanced composite materials have been widely applied as lightweight structures in unmanned aerial vehicles( UAVs) due to their high specific strength and high specific modulus. They also have made contributions to better stealth and shock absorption properties for advanced UAV through integral design for functional and structural components. This paper reviews application of the advanced composites in several typical UAVs,and focuses on the characteristics and the application of the advanced composites in solar powered airplane. At last,the trend of future research in this field is predicted.

Synthesis of Triethanolamine Borate and Evaluation of Its Antirust Performance

Abstract: Triethanolamine borate ester was synthesized from triethanolamine and boric acid at a boric acid / triethanolamine molar ratio of 1. 0 ∶ 1. 2,a reaction temperature of 140 ~ 145 ℃,and a reaction time of 4 h. The chemical structure of as-synthesized triethanolamine borate ester was characterized by infrared spectrometry,and its composition was determined by elemental analysis. Moreover,the hydrolysis stability of the product was evaluated,and the antirust performance of the aqueous solution of as-synthesized product was examined based on immersion tests( No. 20 and No. 45 steel and grey cast iron were used; immersion time was fixed as 10 days). It was found that the solution of 0. 5%( mass fraction; the same hereafter) triethanolamine borate ester exhibited good antirust performance for No. 20 steel. Besides,at an aqueous solution concentration of 0. 6% and 0. 8%,triethanolamine borate ester had good antirust ability for No. 45 steel and grey cast iron,respectively. In the meantime,the solution of 2. 5% triethanolamine borate ester exhibited good antirust ability for the steels and grey cast iron,showing potential as an antirust agent for metal processing.

Optimization of Nickel-Phosphorous Electroless Plating Technology for Whisker-Reinforced Magnesium-Matrix Composite and Study of Corrosion Resistance of Coatings

Abstract: Conventional nickel-phosphorous electroless plating technology was applied to whisker-reinforced A291D Mg alloy-matrix composite so as to improve its corrosion resistance.Thus four kinds of electroless plating conditions were primarily screened,and then further optimized in relation to the morphology of electroless Ni-P coatings and the properties of the electroless plating bath.Moreover,the surface morphology of as-plated Ni-P coatings was observed with a scanning electron microscope,and their corrosion resistance was evaluated by electrochemical method(potentialtime curve,potential-dynamic polarization curve,and alternating current impedance spectrum).The adhesion to substrate was determined by file test.Results indicated that conventional nickelphosphorous electroless plating technology applicable to Mg alloys was also suitable for whisker-reinforced Mg alloy-matrix composite.The optimized electroless plating bath consisted of 20 g/L 2NiCO_3?Ni(OH)_2?H_2O_3 10 g/L NH_4 HF_2,and 20 g/L NaH_2 PO_2 ?H_2O;and the optimized electroless plating condition was suggested as pH value of 6.5,temperature of 65 ?,and time of 2 h.Relevant electroless Ni-P coating obtained under the optimized condition was free of surface defects and had good compactness as well as good adhesion to Mg alloy substrate.Besides, the corrosion potential of electroless Ni-P coating was higher than that of Mg alloy substrate by 0.41 V,showing mildly improved corrosion resistance.

Preparation of Polyamide-Imide Self-Lubricating Composite Paint and Evaluation of Performance of Composite Coating Made of the Paint

Abstract: Polyamide-imide (denoted as PAI) was adopted as the matrix to prepare PAI-based self-lubricating wear-resistant paint in the presence of solid lubricants of MoS2 and polytetrafluroethylene (PTFE) as well as BYK-163 type dispersant and EFKA-3772 type flatting agent PAI-based self-lubricating wear-resistant composite coating was then prepared from as-obtained paint The effect of solid lubricants on the wear resis-tance of as-prepared PAI-based composite coating was investigated with an MRH-3G friction and wear tester,and the morphology of the composite coating before and after friction and wear tests was observed with a scanning electron microscope It was found that, when the contents of MoS2 and PTFE in as-obtained PAI-based self-lubricating wear-resistant paint were 30% (mass fraction; the same hereafter) and 6% respectively, corresponding PAI-based composite coating possessed desired compactness and small porosity as well as excellent corrosion resistance, wear resistance and physical-chemical properties

Synthesis of a Kind of Novel Gemini Imidazoline Quaternary Ammonium Salt Corrosion Inhibitor and Evaluation of Its Inhibiting Performance

Abstract: Oleic acid and diethylenetriamine were adopted as the starting materials to synthesize oleate imidazoline corrosion inhibitor (denoted as OAC) in the presence of dimethylbenzene as the water-carrier Resultant OAC was then allowed to react with the mixed light-yellow intermediate obtained by the quaternization of epoxy chloropropane and diethylamine, yielding a novel gemini imidazoline quaternary ammonium salt corrosion inhibitor (denoted as EOAC) The structure of as-obtained EOAC was analyzed by means of infrared spectrometry, and the corrosion inhibition performance of EOAC and OAC for Q235 steel in the aqueous solutions of HCl with different concentrations was evaluated by static corrosion tests Moreover, the contact angles of water separately containing EOAC and OAC on Q235 steel were measured It was found that, under environment of low acidity, EOAC showed better corrosion inhibition performance and wetting behavior than OAC, and the former was also able to well spread on the surface of iron and steel to form wetting films

Tribological properties analysis of laser surface textured titanium alloy

Abstract: 50 μm、100 μm、150 μm、200 μm aequilate grid strip and 50 μm、100 μm、200 μm diameter distribution pit were formed on surface of tianium alloy by laser etching.Friction-wear test was performed with UMT-2.The surface morphology of wear specimens were observed by scanning electron microscope(SEM).The experimental results show aequilate grid strip and distribution both can store oil,advantage oil film and collect abrasive dust.The friction coefficient of textured surface is reduced,which associated with the texture size and influenced by load.The antifriction effect of the aequilate grid strip is better than distribution pit.The small size texture has low friction coefficient and is easy to wear.50 μm equilate grid strip gets the best effiction of reducing friction coefficient,which is 0.116~0.124 and sustained for a long time under load 1~3 N.100um aequilate grid strip has the best friction coefficient about 0.19 under load 4~6 N.

Effect of Phosphorous Content on Microstructure and Wear Resistance of Electroless Ni-P Alloy Coatings on Titanium Alloy

Abstract: Ni-P alloy coatings with different P contents were successfully prepared on the surface of TC4 titanium alloy by making use of electroless plating technology.The morphology and microstructure of as-prepared Ni-P alloy coatings were analyzed by scanning electron microscopy,energy dispersive spectrometry and X-ray diffraction.Furthermore,the hardness as well as wear mass loss and friction coefficient of as-prepared Ni-P alloy coatings was measured in relation to the effect of P content,and the wear mechanism of the alloy coatings was discussed.It was found that the amount of hump-like structure and grain boundary of Ni-P coatings gradually decreased with increasing P content,and the size of the grains gradually increased therewith,which was accompanied by crystal to amorphous transformation.Besides,the hardness and friction coefficient of the alloy coatings declined with increasing P content,and their wear mass loss rose therewith.In the meantime,as-prepared electroless Ni-P coatings with low P contents were dominated by abrasive wear and mild adhesion wear,while those with moderate and high P contents were dominated by severe adhesion wear and abrasive wear.