高分子专业本科教学中开设《涂料学》课程的探索

本文根据高分子专业的培养目标,提出在高等院校高分子专业本科教学中开设《涂料学》课程的意义,针对课程的特点,对教学内容和教学方法进行了初步探索。

纳米SiO_2和发泡剂对聚氨酯防火涂料阻燃性能的影响

近几年来我国火灾的严重性已使木材阻燃成为一项紧迫任务。为了提高马尾松胶合板的阻燃性能,以聚氨酯为对象,采用HRR3热释放率系统、HC-2氧指数测定仪等测定了涂覆膨胀型纳米聚氨酯防火涂料的马尾松胶合板的燃烧热释放率和氧指数,分析了纳米SiO2以及各种发泡剂对聚氨酯防火涂料阻燃性能的影响,并分析它们的阻燃机理。结果表明,在聚氨酯防火涂料中加入纳米SiO2,可使涂覆的胶合板燃烧失重和炭化体积明显降低,有效地提高阻燃性能,纳米SiO2用量以3%为宜。加入发泡剂可进一步提高涂料的阻燃效果和氧指数值。复合发泡剂比单一发泡剂效果好。在8种试验方案中,用尿素-双氰胺按1∶3的质量比组成的复合发泡剂阻燃效果最优,在HRR3热释放率系统测试中,涂覆的胶合板着火燃烧时间最长(69s),达最高热释放率时间最短(130s),热释放率峰值最低(53.45kW/m2),氧指数值最高(55)。

Tensile properties and hot extrusion behavior of Zn O-coated Mg_2B_2O_(5w)/6061 Al composites

The 6061 aluminum matrix composites reinforced with ZnO-coated Mg_2B_2O_5w were fabricated by squeeze casting method and followed by extruded under a technical equivalent condition. The mechanical properties and microstructures of the composites were investigated. The results showed that the elastic modulus of the as-cast composites increased straightly with increasing ZnO coating content. The ultimate tensile strength and yield strength of the as-cast composites rapidly increased initially and then declined with increasing ZnO coating content. However, the elongations of all the as-cast composites had similar values. The elongations of the composites were highly enhanced and the ultimate tensile strength of the composite without ZnO coating was the largest after extrusion. A number of whiskers in the composites with ZnO coating were fractured during the extrusion process, but the whiskers＇ breakage extent was limited with the increase of coating content.

Influence of carbon coating prepared by microwave pyrolysis on properties of LiNi_(1/3) Mn_(1/3) Co_(1/3) O_2

A novel synthesis method of carbon-coated LiNil/3Mnl/3COl/302 cathode material for lithium-ion battery was reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The prepared powders were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, X-ray fluorescence （XRF） and charge/discharge tests. XRD results indicate that the carbon coating does not change the phase structure of LiNil/3Mnl/3C01/302 material. SEM results show that the surface of spherical carbon-coated material becomes rough. Electrochemical performance results show that the carbon coating can improve the cycling performance of LiNii/3Mnl/3C01/302. The specific discharge capacity retention of the carbon-coated LiNi1/3Mnt/3Col/30z reached 85.0%-96.0% at the 50th cycle at 0.2C rate, and the specific discharge capacity retention is improved at a high rate.

Effect of Multiple Coatings of One-step Self-etching Adhesive on Microtensile Bond Strength to Primary Dentin

Objective To investigate the effect of multiple coatings of the one-step self-etching adhesive on immediate microtensile bond strength to primary dentin.Methods Twelve caries-free human primary molars were randomly divided into 2 groups with 6 teeth each.In group 1,each tooth was hemisected into two halves.One half was assigned to control subgroup 1,which was bonded with a single-step self-etching adhesive according to the manufacturer's instructions;the other half was assigned to experimental subgroup 1 in which the adhesive was applied three times before light curing.In group 2,the teeth were also hemisected into two halves.One half was assigned to control subgroup 2,which was bonded with the single-step self-etching adhesive according to the manufacturer's instructions;the other half was assigned to experimental subgroup 2 in which three layers of adhesive were applied with light curing each successive layer.Microtensile bond strength was immediately tested after specimen preparation.Results When the adhesive was applied three times before light curing,the bond strength of the experimental subgroup 1(n=33,57.49±11.61 MPa) was higher than that of the control subgroup 1(n=31,49.71±11.43 MPa,P<0.05).When using the technique of applying multiple layers of adhesive with light curing each successive layer,no difference of immediate bond strength was observed between the control subgroup 2 and the experimental subgroup 2(P>0.05).Conclusion Multiple coatings of one-step self-etching adhesive can increase the immediate bond strength to primary dentin when using the technique of light-curing after applying three layers of adhesive.

Effects of dip-coated BN interphase on mechanical properties of SiC_f/SiC composites prepared by CVI process

BN interphase was successfully synthesized on SiC fiber fabrics by dip-coating process using boric acid and urea as precursors under N2 atmosphere. The morphology of BN interphase was observed by SEM, and the structure was characterized by XRD and FT-IR spectra. The SiCf/SiC composites with dip-coated BN interphase were fabricated by chemical vapor infiltration （CVI） process, and the effects ofBN interphase on the mechanical properties of composites were investigated. The results show that the SiC fibers are fully covered by BN interphase with smooth surface and turbostratic structure （t-BN）, and the thickness is about 0.4 μm. The flexural strengths of SiCf/SiC composites with and without BN interphase are about 180 and 95 MPa, respectively. Compared with the as-received SiCf/SiC composites, the composites with BN interphase exhibit an obvious toughened fracture behavior. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in protecting the fibers from chemical attack during matrix infiltration and weakening interfacial bonding, which can improve the mechanical properties of SiCf/SiC composites remarkably.

Improved wettability and mechanical properties of metal coated carbon fiber-reinforced aluminum matrix composites by squeeze melt infiltration technique

In order to improve the wettability and bonding performance of the interface between carbon fiber and aluminum matrix,nickel-and copper-coated carbon fiber-reinforced aluminum matrix composites were fabricated by the squeeze melt infiltration technique.The interface wettability,microstructure and mechanical properties of the composites were compared and investigated.Compared with the uncoated fiber-reinforced aluminum matrix composite,the microstructure analysis indicated that the coatings significantly improved the wettability and effectively inhibited the interface reaction between carbon fiber and aluminum matrix during the process.Under the same processing condition,aluminum melt was easy to infiltrate into the copper-coated fiber bundles.Furthermore,the inhibited interface reaction was more conducive to maintain the original strength of fiber and improve the fiber−matrix interface bonding performance.The mechanical properties were evaluated by uniaxial tensile test.The yield strength,ultimate tensile strength and elastic modulus of the copper-coated carbon fiber-reinforced aluminum matrix composite were about 124 MPa,140 MPa and 82 GPa,respectively.In the case of nickel-coated carbon fiber-reinforced aluminum matrix composite,the yield strength,ultimate tensile strength and elastic modulus were about 60 MPa,70 MPa and 79 GPa,respectively.The excellent mechanical properties for copper-coated fiber-reinforced composites are attributed to better compactness of the matrix and better fiber−matrix interface bonding,which favor the load transfer ability from aluminam matrix to carbon fiber under the loading state,giving full play to the bearing role of carbon fiber.

Cavitation and electrochemical characteristics of thermal spray coating with sealing material

Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al-14.5%Zn-0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silieon sealing material shows the best anti-cavitation characteristics.

Tribology Performance and Adhesive Strength Evaluation of TiAlSiN Coating

Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAISiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch test were calculated and the values are 30.84 MPa and 4.98 MPa respectively. The average friction coefficients of TiAISiN coat- ing against 2Crl2Ni4Mo3VNbN steel are 0.70 （sliding speed 50 m/rain）, 0.63 （sliding speed 100 m/min）, and 0.81 （sliding speed 150 m/min）. The elements diffusion was analyzed by EDS. A1 and Si element of coating material dif- fuse to the steel disc, except Ti element. The oxidation decreases with the increase of sliding speed, but the adhesion increases with the increase of sliding speed. More A1 element diffuses to the steel disc at the high sliding speed, but the diffusion of Si element keeps almost constant at dlfferent sliding speeds.

Study of the Adherence Mechanism Between the Metal and Inorganic Coating with Mill Addition of Li_2Ni_8O_(10) Nano Powder

The adherence strength between the metal and the inorganic coating can be greatly increased by mill addition of Li2Ni8O10. The interface structure between metal and the inorganic coating with excellent adherence has been studied by investigating the chemical composition and the microstrncture as well as elements valence bond on the interface with the help of scanning electron microscope （SEM）, electron microprobe, and Auger elctron spectroscope （AES）. The results show that there is a non-stoichiometrieal transitional layer on the interface between metal and the inorganic coating with excellent adherence, the adherence between metal and the non-stoichiometrical transitional layer is achieved by the metallic bond and the adherence between the non- stoichiometrical transitional layer and the inorganic coating is produced by ionic and covalent bond. The non-stoichiometrical transitional layer results in the strong adherence.

Effects of Cr interlayer on mechanical and tribological properties of Cr-Al-Si-N nanocomposite coating

Cr-A1-Si-N coatings were deposited on SUS 304 substrate by a hybrid coating system. A Cr interlayer was introduced between Cr-A1-Si-N coating and SUS 304 substrate to improve the coating adherence. The effects of Cr interlayer on the microhardness, adhesion, and tribological behavior of Cr-A1-Si-N coatings were systematically investigated. The results indicate that the microhardness of the Cr-A1-Si-N coatings gradually deceases with increasing thickness of Cr interlayers. The adhesion between Cr-A1-Si-N and SUS 304 substrate is improved by addition of the Cr interlayers. A peak critical load of-50 N is observed for the coating containing Cr interlayer of 60 nm as compared - 20 N for the coating without Cr interlayer. The thicker Cr interlayers result in reduced critical load values. Moreover, the wear resistance of the Cr-AI-Si-N coatings is greatly enhanced by introducing the Cr interlayer with thickness of 60 nm in spite of the decreased microhardness. The friction coefficient of the coating system is also moderately reduced.

Electroless Co-Zn Surface-Modified Nickel Hydroxide as an Active Material for Pasted Nickel Electrodes

Chemically precipitated β type nickel hydroxide powder was surface modified by electroless deposition of Co Zn coatings,and physical properties of both the modified and unmodified nickel hydroxide were characterized by scanning electron microscopy (SEM), specific surface area (BET), X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS). It has been found that Co and Zn components of the surface electroless coatings exist in the oxidized state. Electrochemical performances of pasted nickel electrodes using the modified nickel hydroxide as an active material were investigated, and compared with those of the electrodes prepared with the unmodified nickel hydroxide. Charge/discharge tests show that the modified nickel hydroxide electrodes exhibit better performances in the charge efficiency, specific discharge capacity and active material utilization. Their resistance to swelling with cycling is also superior to that of the unmodified nickel hydroxide electrodes. Cyclic voltammetric (CV) studies indicate that the modified electrodes have a higher electrochemical activity, and the porous pasted nickel electrodes have some distinguished CV characteristics in comparison with those of the thin film nickel electrodes.

Mechanical Properties of Ni-Coated Single Graphene Sheet and Their Embedded Aluminum Matrix Composites

The effects of Ni coating on the mechanical behaviors of single graphene sheet and their embedded Al matrix composites under axial tension are investigated using molecular dynamics （MD） simulation method. The results show that the Young＇s moduli and tensile strength of graphene obviously decrease after Ni coating. The results also show that the mechanical properties of Al matrix can be obviously increased by embedding a single graphene sheet. From the simulation, we also find that the Young＇s modulus and tensile strength of the Ni-coated graphene/Al composite is obviously larger than those of the uncoated graphene/Al composite. The increased magnitude of the Young＇s modulus and tensile strength of graphene/Al composite are 52.27% and 32.32% at 0.01 K, respectively, due to Ni coating. By exploring the effects of temperature on the mechanical properties of single graphene sheet and their embedded Al matrix composites, it is found that the higher temperature leads to the lower critical strain and tensile strength.

Mechanical properties of AISI 1045 ceramic coated materials by nano indentation and crack opening displacement method

Abstract： An effective approach was conducted for estimating fracture toughness using the crack opening displacement （COD） method for plasma enhanced chemical vapor deposition （PECVD） coating materials. For this evaluation, an elastoplastic analysis was used to estimate critical COD values for single edge notched bending （SENB） specimens. The relationship between fracture toughness （Kic） and critical COD for SENB specimens was obtained. Microstructure of the interface between AleO3-TiO2 composite ceramic coatings and AISI 1045 steel substrates was studied by using scanning electron microscope （SEM）. Chemical compositions were clarified by energy-dispersive X-ray spectroscopy （EDS）. The results show that the interface between of Al203-TiO2 and substrate has mechanical combining. The nanohardness of the coatings can reach 1 200 GPa examined by nanoindentation. The Klc was calculated according to this relationship from critical COD. The bending process produces a significant relationship of COD independent of the axial force applied. Fractographic analysis was conducted to determine the crack length. From the physical analysis of nanoindentation curves, the elastic modulus of 1045/AI2O3-TiO2 is 180 GPa for the 50 μm film. The highest value of fracture toughness for 1045/A1203-TiO2-250 μm is 348 MPa·mv2.

展示 合作 交流 发展——2004’世界华人高科技化学暨涂料、涂装、防腐蚀学术技术交流会在成都胜利闭幕

2004年8月7日-9日世界华人高科技化学暨涂料、涂装、防腐蚀学术技术交流会在中国成都锦江大礼堂隆重举行。广场上彩旗飞扬，人头攒动。礼堂正上方悬挂着两条巨大横幅“热烈庆祝世界华人涂料、涂装、防腐蚀学术技术交流会隆重召开”、“热烈庆祝世界华人高科技化学研讨会隆重召开”赫然醒目，两旁“双赢通”标志充分体现出信息网络与双赢时代的到来。

Advanced cold spray technology:Deposition characteristics and potential applications

Cold spray technology,originated from the Institute of Theoretical and Applied Mechanics Siberian branch of the Russian Academy of Sciences,is a rapidly emerging industrial coating technology.Cold sprayed particles with high-velocity impact onto a substrate so as to induce severe plastic deformation and then create a deposit.For its low temperature and high velocity compared with thermal spraying,the cold spraying process is increasingly used in the industries for protective coating.The deposition characteristics of the particles,coating formation and bonding mechanism of the cold spraying process are different from thermal spraying.Many theory investigations of the cold spraying process contribute to the development of the high performance coatings,which makes the cold spraying process as a popular research field.Presently,the deposition characteristics,bonding mechanism,process optimization as well as classical applications of the cold spraying technology in the past are reviewed,and the interesting points for the further development,optimization and applications of this technology are also recommended.

The black pottery coating of longshan times from Taosi Site

Taosi is an archaeological site in Xiangfen county, Shanxi province. It is considered as a capital city site with the rudiment of an early country in Longshan Times. In this work, the black pottery coating was found on the surface of black and grey pottery of Longshan times and confirmed by scientific studies for the first time. It filled in the blank of pottery coating study in this time period at the Yellow River Valley, as well as supplied a new study method of "black skin pottery" besides the carburization craft. In addition, according to the archaeological materials, we inferred that the wares with this pottery coating might be only used by the nobility at that time.