首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 125 毫秒
1.
Inorganic/organic hybrid coatings were prepared using epoxidized linseed oil with combinations of the two sol–gel precursors (titanium(IV) isopropoxide, tetraethyl orthosilicate), and a telechelic silicate based on a modified oligomeric caprolactone. The coatings were UV-cured with sulfonium initiators which concomitantly cured the epoxy functional organic phase and the sol–gel inorganic phase to form a co-continuous inorganic/organic system. A ternary experimental design was employed to elucidate the influence of inorganic modifier on the mechanical properties of the inorganic/organic hybrid coatings. Small angle X-ray scattering (SAXS) was used to evaluate radius of gyration of the metal-oxo-cluster. Various coating properties, such as hardness, impact resistance, adhesion, solvent resistance, and surface energy were investigated as a function of sol–gel precursors. Inorganic/organic hybrid coatings containing both tetraethyl orthosilicate and the modified caprolactone resulted in improved hardness and solvent resistance with no loss of impact strength. The inclusion of titanium(IV) isopropoxide in to the systems resulted in a systematic reduction in the coatings properties. This was attributed to inhibition of the organic crosslinking process as a consequence of absorption of ultraviolet light by the titanium-oxo-clusters.  相似文献   

2.
溶胶-凝胶/环氧杂化涂料的应用   总被引:1,自引:0,他引:1  
溶胶-凝胶/环氧杂化涂料的配方已经进行了研究,杂化涂料具有更强的机械强度(如硬度),更加耐磨蚀。当固化温度提高到80℃,全部研究的杂化涂料都能通过湿性黏结试验,但在室温下固化时仅有部分的杂化涂料通过湿性黏结试验。多数杂化涂料在室温下固化时对水的敏感性问题尚待解决。  相似文献   

3.
Current coating systems for aircraft corrosion protection are based on a traditional chromate surface treatment, primer, and topcoat. The Air Force is seeking environmentally benign corrosion-resistant surface treatments for aluminum-skinned aircraft as a replacement for environmentally hazardous surface treatments involving chromates. Performance of replacement treatments must be able to satisfy the durability needed for dramatically extended lifetimes, be compatible with present and future environmental requirements, and be easily integrated into current primer/topcoat paint systems.

Organically modified zirconate sol–gel films were investigated as an environmentally compliant replacement for chromated surface treatments, which included functionalized components to tailor the chemistry at both the aluminum oxide substrate/surface treatment interface and the surface treatment/topcoat interface. Sol–gel films were applied to aluminum 2024-T3 alloy coupons, and the resulting film chemistry was investigated. FTIR was used to identify organic components in the film and X-ray photoelectron spectroscopy was used to investigate the interface chemistry. The result of the chemically modified sol–gel synthesis was a coating in which a concentration gradient was formed at the surface, which is discussed. The corrosion protection attributes of these films was also studied and the electrochemical evaluation of sol–gel films will be discussed, both as stand-alone coatings and as part of a full coating system.

Organically modified sol–gels exhibited significantly better protection in terms of barrier properties in comparison to a typical chromate-based processes. The resulting data from evaluations of sol–gel produced coatings show promise towards the goal of producing a robust chemical interaction/bonding of such corrosion-resistant coatings on the surface of aluminum-skinned aircraft without the use of environmentally hazardous chromate agents.  相似文献   


4.
The advanced corrosion resistant aircraft coatings program (ACRAC) is part of the Air Force strategy to improve performance and reduce environmental impact of coatings used on Air Force weapon systems. The program addresses the Air Force near and mid-term strategies to eliminate chromate corrosion inhibitors and reduce steps in the outer mold line coating process. Evaluation of the coating process (surface preparation, conversion coating, primer, topcoat) as a system is a key feature of the ACRAC program. Results to date indicate that the current-state-of-the-art nonchromated coating systems are significantly less effective than those with chromate. A chromate conversion coating is required for the nonchromate primer system to meet minimum requirements. Sol–gel-process based conversion coatings can replace chromate conversion coatings provided a chromated primer is used. Several approaches to incorporating inhibitors into sol–gel coatings are discussed. Electrochemical methods for testing coating performance are discussed and a new procedure based on impedance spectroscopy for evaluating active damage repair is presented.  相似文献   

5.
Organic–inorganic hybrid coatings based on fluorinated/methacrylated soybean oil and bisphenol A/F epoxy methacrylate were obtained by combining photopolymerization and sol–gel process. Hard and transparent hybrid coatings were prepared on polycarbonate panels and their physical and mechanical properties such as gel content, hardness, adhesion, gloss, contact angle as well as tensile strength were measured. Results from the mechanical measurements showed that the properties of hybrid coatings improved with the increase in fluorine and sol–gel precursor contents. Thermo gravimetric analysis results demonstrated that fluorine and silica incorporations significantly enhanced the thermal oxidative stability of the hybrid coating materials. The surface morphology was also characterized by scanning electron microscopy (SEM). SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.  相似文献   

6.
The effects of multiwalled carbon nanotube (MWCNT) content on the adhesion strength and wear and corrosion resistance of the epoxy composite coatings prepared on aluminum alloy (AA) 2024-T3 substrates were evaluated using atomic force microscopy (AFM), blister test, ball-on-disk micro-tribological test and electrochemical impedance spectroscopy (EIS). The adhesion strength of the epoxy composite coatings improved with increasing MWCNT content. Increased MWCNT content also decreased the friction coefficient and increased the wear resistance of the epoxy composite coatings due to improved solid lubricating and rolling effects of the MWCNTs and the improved load bearing capacity of the composite coatings. Finally, EIS indicated that increased MWCNT content increased the coating pore resistance due to a decreased porosity density, which resulted in an increase in the total impedance of the coated samples.  相似文献   

7.
UV curable, hard, and transparent organic–inorganic hybrid coatings with covalent links between the inorganic and the organic networks were prepared by the sol–gel method. These hybrid coating materials were synthesised using a commercially available, acrylate end-capped polyurethane oligomeric resin, hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (MPTMS) as a coupling agent between the organic and inorganic phase, and a metal alkoxide, tetraethylorthosilicate (TEOS). The materials were applied onto polycarbonate sheets and UV cured, followed by a thermal treatment to give a transparent coating with a good adhesion and abrasion resistance. The high transmission and the thermogravimetric behaviour indicate the presence of a nanoscale hybrid composition. In a taber abrasion test, uncoated polycarbonate sheets exhibit a 48% decrease in light transmittance at 633 nm after 300 wear cycles, whereas the hybrid coating system containing 10 wt% silica shows only 10% decrease in light transmittance. For obtaining antistatic coatings, an intrinsically conductive polymer (ICP) was added to the optimised coating formulation. It is shown that the surface resistivity of the organic–inorganic hybrid coating can be reduced from 1016 to 106 Ω for a high concentration of ICP in the coating formulation.  相似文献   

8.
Protective space coatings: a ceramer approach for nanoscale materials   总被引:3,自引:0,他引:3  
There is a concerted and focused push to develop protective space coatings for vehicles in low earth and geosynchronous orbit. The space environment is not suitable for organic materials due to atomic oxygen, high energy particles, and deep UV light being able to degrade polymeric organic resins. An inorganic/organic hybrid coating, known as a ceramer, will be fabricated using a polysiloxane binder and nanophase silicon/metal-oxo-clusters derived from sol–gel precursors. The binder of the coating will be a substituted polysiloxane terminated with a cyclohexyl epoxide. The cyclohexyl epoxide will be cured at ambient temperature via a cationic UV curing mechanism. PDSC will also be used to investigate the effects of temperature, UV light intensity, sol–gel precursor concentration, and exposure time have on the rate of polymerization. Nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to characterize the synthesis of the polysiloxanes. The rate of polymerization was found to increase as temperature, intensity, sol–gel precursor concentration, and exposure time were increased.  相似文献   

9.
Inorganic/organic hybrid conversion surface coatings for long-term protection of aluminum alloys against atmospheric corrosion have been developed based on a unique self-assembled nanophase particle (SNAP) coating process. Nano-particles with peripheral epoxy functional groups are pre-formed in an aqueous sol–gel process and then assembled and crosslinked upon application on the substrate surface. Mono-, di-, and tri-functional amino-silanes have been used as crosslinking agents. Corrosion resistance properties of these hybrid nanocomposite coatings studied by a variety of electrochemical testing methods including electrochemical impedance spectroscopy, scanning vibrating electrode technique, and potentiodynamic scan method, indicate excellent barrier protection performance of the coatings. For comparison, coatings crosslinked with amino-silanes offer significant improvement in coating performance over the previously described SNAP formulations with a conventional amine crosslinker—diethylenetriamine.  相似文献   

10.
High performance polyaniline containing coating system for wet surfaces   总被引:1,自引:0,他引:1  
Application of paint coatings on wet surfaces is rather difficult due to poor adhesion of coatings. For painting of wet surfaces, moisture curable coating systems based on epoxy resin and ketimine are found to be useful. Hence a study has been made on the corrosion protection ability of coating on wet surfaces using epoxy resin, ketimine and polyaniline. Paints with 20–30% PVC were prepared and applied over the wet steel surface and the corrosion protection performance of the coating was found out by salt spray and electrochemical impedance spectroscopic techniques. Coating with 20% PVC is found to offer very high protection since the impedance values are remained at greater than 109 Ω cm2 after immersion and salt spray tests.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号