Improvement strategy on thermophysical properties of A_(2)B_(2)O_(7)-type rare earth zirconates for thermal barrier coatings applications:A review

The A_(2)B_(2)O_(7)-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating(TBC) materials because of their low sintering rate,improved phase stability,and reduced thermal conductivity in contrast with the currently used yttria-partially stabilized zirconia (YSZ) in high operating temperature environments.This review summarizes the recent progress on rare earth zirconates for TBCs that insulate high-temperature gas from hot-section components in gas turbines.Based on the first principles,molecular dynamics,and new data-driven calculation approaches,doping and high-entropy strategies have now been adopted in advanced TBC materials design.In this paper,the solid-state heat transfer mechanism of TBCs is explained from two aspects,including heat conduction over the full operating temperature range and thermal radiation at medium and high temperature.This paper also provides new insights into design considerations of adaptive TBC materials,and the challenges and potential breakthroughs are further highlighted for extreme environmental applications.Strategies for improving thermophysical performance are proposed in two approaches:defect engineering and material compositing.

Preparation and characterization of LPPS NiCoCrAlYTa coatings for gas turbine engine

NiCoCrAlYTa coatings have been deposited onto an aircraft gas turbine engine blade using a LPPS unit equipped with a computerized robot. Optimal processing conditions, including spray parameters, the trajectory of the robot, and the synchronized movements between the torch and the blade, have been developed for superior coating properties. Transferred arc treatment, providing a preheating and a cleaning of the substrate surface, enhances the adherence of the coatings to the substrate. The resulting LPPS coatings show dense and uniform characteristics with ideal hardness, and good corrosion resistance to cycle oxidation.

Study on β-TCP Coated Porous Mg as a Bone Tissue Engineering Scaffold Material

Three-dimensional honeycomb-structured magnesium （Mg） scaffolds with interconnected pores of accurately controlled pore size and porosity were fabricated by laser perforation technique. Biodegradable and bioactiveβ- tricalcium phosphate （β-TCP） coatings were prepared on and the biodegradation mechanism was simply evaluated the porous Mg to further improve its biocompatibility, in vitro. It was found that the mechanical properties of this type of porous Mg significantly depended on its porosity. Elastic modulus and compressive strength similar to human bones could be obtained for the porous Mg with porosity of 42.6%-51%. It was observed that the human osteosarcoma cells （UMR106） were well adhered and proliferated on the surface of the β- TCP coated porous Mg, which indicates that theβ-TCP coated porous Mg is promising to be a bone tissue engineering scaffold material.

Optimization and design of pigments for heat-insulating coatings

This paper reports that heat insulating property of infrared reflective coatings is obtained through the use of pigments which diffuse near-infrared thermal radiation. Suitable structure and size distribution of pigments would attain maximum diffuse infrared radiation and reduce the pigment volume concentration required. The optimum structure and size range of pigments for reflective infrared coatings are studied by using Kubelka-Munk theory, Mie model and independent scattering approximation. Taking titania particle as the pigment embedded in an inorganic coating, the computational results show that core-shell particles present excellent scattering ability, more so than solid and hollow spherical particles. The optimum radius range of core-shell particles is around 0.3 - 1.6 μm. ~rthermore, the influence of shell thickness on optical parameters of the coating is also obvious and the optimal thickness of shell is 100-300 nm.

Evaluation of ring surfaces with several coatings for friction,wear and scuffing life

Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission.Many engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating period.Therefore,it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel engine.Wear and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel engine.The frictional forces,wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear tester.The tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed pin.Several coatings on the ring specimen were used,such as DLC,TiN,Cr-ceramic and TiAlN,in order to improve the tribological characteristics of the ring.The coefficients of friction were monitored during the tests,and the wear volumes of the piston ring surfaces with various coatings were compared.Test results show that the DLC coating exhibits better tribological properties than the other coatings.The graphite structure of this coating is responsible for the low friction and wear of the DLC film.The TiN and DLC coatings show better scuffing resistance than the other coatings.The TiN and Cr-ceramic coated rings show good wear resistance and high friction.

The Application Prospect Autologous Bone Marrow Extract Buffy Coat in Cartilage Tissue Engineering: A Mini-Review

Cartilage injury is an important cause of osteoarthritis;however, there is no effective method of cartilage regeneration at present. Therefore, it would be of great value to explore and develop new methods of cartilage regeneration. In recent years, it has become a hot topic on repairing damaged cartilage by using tissue engineered cartilage domestic and abroad. It’s the key factor to success for getting cell source which is effective, applicable and easy to obtain in the technology of cartilage tissue engineering filed. This article summarizes the research progress of bone marrow extract buffy coat in cartilage tissue engineering.

Tribological Properties of Ti-DLC Coatings on Piston-pin Surfaces

A magnetically filtered cathode vacuum arc deposition system was used to deposit Ti-doped diamond-like carbon coatings(Ti-DLC)on pin surfaces to improve the wear resistance of high-power density diesel engine piston pins.The coating structure,composition,and morphology were characterised using field emission scanning electron microscopy(FE-SEM),X-ray photoelectron spectroscopy(XPS),Raman spectroscopy,and other techniques.Friction tests were carried out using a universal tribometer to study the tribological properties of pins with or without coatings under dry friction and oil lubrication.The surface morphology and cross-sectional morphology of the Ti-DLC coating show that the coating has a uniform crosssection and good surface properties.The XPS spectrum shows that the coating contains Ti-C,Ti-C*,sp2-C,sp3-C,and C-O/C=O.Raman spectroscopy shows that there is an amorphous carbon phase in the Ti-DLC coating.The friction test shows that the friction temperature increase of the pin with the Ti-DLC coating is lower than that without the coating,especially under dry-friction conditions.At the end of the test,the difierence in temperature increase is 16.7%.The friction coefficient when using high-viscosity lubricating oil with a coating is relatively lower than that without a coating,especially under low-speed and heavy-duty conditions.In the dryfriction state,the coated surface has better wear resistance than the uncoated surface,which primarily manifests as abrasive wear,and the surface without a coating mainly experiences adhesive wear.

Improvement on Performances of Internal Combustion Engine Using the Technology of Ceramic Coating

This paper introduces a new technology of using ceramic coating on piston rings of an internal combustion engine, and the comparison of mechanical efficiency and performances of an actual engine before and after the application of ceramic coating on the piston rings. The experimental results show that the mechanical efficiency and power output are enhanced by 4% and 2.6%, respectively, with fuel consumption reduced by (2.9%.) Further studies on coating processing and coating materials as well as the reliability and durability will be of great significance in the application and popularization of the new technology.

Effect of coating repair on microstructure and mechanical properties of Ni_3Al based alloy IC6

The effect of coating repair on microstructure and mechanical properties of a directionally solidified nickel base alloy IC6 was studied. The experimental results show that after coating repair treatment, the substrate/coating interface keeps well, and the combination of coating and substrate is very good, as well as very slight mutual diffusion of alloying elements between substrate and coating occurred. Although coating repair treatment make diffusion time double, only a little amount of Mo diffused into coating, and the elements Cr and Co of NiCoCrAlYHf coating only exist in a thin layer of influence region of the substrate, which has no obvious effect on the microstructure of alloy IC6. Tensile tests at room temperature and stress rupture tests under 1?100?℃, 90?MPa of the coating repaired sample were conducted. The results show that the coating repair has no evident effect on mechanical properties. Therefore, it may be considered that when the coating is unexpectedly destroyed, it can be repaired.

Coating Protection for Production Facilities of Offshore Oil Fields

This paper describes coating protection of production facilities of offshore oil fields based on the practice of development of Bohai Offshore Oil Field, with focus laid on the selection of coating systems, surface preparation, coating application, as well as coating inspection for four types of major production facilities.

Numerical Simulation of the Thin Film Coating Flow in Two-Dimension

Thin film coating is a process of making liquid film cover and deposit base body surface by the way of dipping, spraying, sliding or spin coating, which is a kind of modern surface engineering. It plays an important role in the actual processing, such as improving the surface properties, fine processing, and new surface properties. Analysis of the influence of substrating morphology and fluid flow properties itself on coating fluid motion has an important significance to optimize the thin film coating and improve the quality of the final film. The influence from uneven substrate surface’s geometry configuration on internal motion of the flow field in slip-coating is analyzed by using the FLUENT software as a calculation platform. A two-dimension model of slip coating under isosceles triangle and isosceles trapezoid substrate was established, and thin film coating fluid motions under different configuration parameters were simulated. It is pointed out that the key factor determining the turbulence generation and evolution is the parameter of substrating surface nature. The effects of the change of Reynolds number on turbulent appearance and action area are studied. The velocity contours of fluid field on different substrate surfaces are shown, and the impact of substrate geometry on the backwater region is analyzed.

船舶内燃机摩擦学研究进展

对船舶中高速机摩擦学领域的最新研究进展进行综述,重点探讨缸套−活塞环组、曲轴−轴瓦、凸轮机构等关键摩擦副的设计仿真、表面减摩耐磨涂层材料以及试验监测技术等。相关进展表明,通过优化摩擦副的设计与材料选择,应用先进的表面涂层技术和试验监测手段,可以显著提高船舶内燃机的性能和寿命,降低摩擦损失和磨损。相关研究可为未来船舶内燃机摩擦学技术的研究与应用提供参考。

A comprehensive review of thermally sprayed abradable sealing coatings:Focusing on abradability

Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running clearances between the rotating and stationary components.The main benefit of reduction in the clearances is efficiency gains,resulting in lowered fuel consumption and polluting gas emissions,with ecological and economic advantages.However,at these undersized clearances,some rubbing interactions are unavoidable,which can be accommodated by applying Abradable Sealing Coatings(ASCs)on the stationary inner surface.This paper reviews the commercially available abradable materials for thermal spraying at various application positions and temperatures.Emphasis is placed on the abradability and wear mechanisms involved.In addition,considering the tendency of SiC/SiC ceramic matrix composites replacing superalloys as hot section components,the future prospect of ceramic abradables based on Environmental Barrier Coatings(EBCs)in turbine stages is summarized and a new concept of"self-degradable ceramics"based on the corrosive steam environment is proposed for the purpose of high-temperature fillerfree abradables.

JAS COAT固化剂对磷石膏环境风险的影响

磷石膏是湿法生产磷酸的副产物,大量堆存的磷石膏给环境造成了巨大的压力。通过室内理化性质试验研究了JAS COAT固化剂对磷石膏性能的改良,优选出适宜的JAS COAT固化剂掺量及含水率,并对稳定化机理进行了探讨。结果表明,加水及固化剂不能改变磷石膏中重金属的总量,但明显降低了浸出液中重金属的质量浓度;固化剂掺量为3%~5%时,磷石膏的放射性随含水率增加呈先减小后增大的趋势。

Nano surface engineering and remanufacture engineering

Nano surface engineering and remanufacture engineering are introduced, and the relationship between them is set forth. It points out the superiority of nano surface engineering to the traditional one, and reveals the advantages of remanufacture engineering. Taking some nano surface techniques as samples, such as nano-materials brush electroplating, nano-materials thermal spraying and nano-materials self-repairing antifriction additive technology, it shows the applications of nano surface engineering technology to remanufacturing mechanical parts.

Interface Reversible Electric Field Regulated by Amphoteric Charged Protein-Based Coating Toward High-Rate and Robust Zn Anode

Metallic interface engineering is a promising strategy to stabilize Zn anode via promoting Zn^(2+) uniform deposition.However,strong interactions between the coating and Zn^(2+) and sluggish transport of Zn^(2+) lead to high anodic polarization.Here,we present a bio-inspired silk fibroin(SF)coating with amphoteric charges to construct an interface reversible electric field,which manipulates the transfer kinetics of Zn^(2+) and reduces anodic polarization.The alternating positively and negatively charged surface as a build-in driving force can expedite and homogenize Zn^(2+) flux via the inter-play between the charged coating and adsorbed ions,endowing the Zn-SF anode with low polarization voltage and stable plating/stripping.Experimental analyses with theo-retical calculations suggest that SF can facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+) and provide nucleation sites for uniform deposition.Consequently,the Zn-SF anode delivers a high-rate performance with low voltage polarization(83 mV at 20 mA cm^(−2)) and excellent stability(1500 h at 1 mA cm^(−2);500 h at 10 mA cm^(−2)),realizing exceptional cumulative capacity of 2.5 Ah cm^(−2).The full cell coupled with Zn_(x)V_(2)O_(5)·nH_(2)O(ZnVO)cathode achieves specific energy of~270.5/150.6 Wh kg^(−1)(at 0.5/10 A g^(−1))with-99.8% Coulombic efficiency and retains~80.3%(at 5.0 A g^(−1))after 3000 cycles.

Composite ceramics thermal barrier coatings of yttria stabilized zirconia for aero-engines

Composite ceramics thermal barrier coatings(TBCs) are widely used in the aero-engines field due to their excellent thermal insulation, which improves the service life and durability of the inherent hot components. The most typical, successful and widely used TBCs material is yttria stabilized zirconia(YSZ). In this paper, fabrication methods, coating structures, materials, failure mechanism and major challenges of YSZ TBCs are introduced and reviewed. The research tendency is put forward as well. This review provides a good understanding of the YSZ TBCs and inspires researchers to discover versatile ideas to improve the TBCs systems.

A New Type Anticorrosion Coating for Ocean Reinforced Concrete Structures

Corrosion of reinforced concrete structures is a serious problem in ocean engineering. As an orientation of study, anticorrosion coating technique is developed and widely applied, but many problems need to be solved. LSW-2 type anticorrosion coating for maritime reinforced concrete structures is characterized by sea water resistance, salt fog resistance, moisture and heal resistance as well as impermeability to chlorions. The new type coating can be applied to wet concrete surface by conventional construction technique. It is a breakthrough in solving the above mentioned problem. The paper mainly introduces the test results, the property indices, coating procedure, construction technique and economic benefit of Ihe coating.

基于AutoForm的锌铝镁镀层板拉深成形及回弹研究

针对汽车发动机罩外板拉深成形中可能出现的开裂、起皱、塑性变形不足及回弹等缺陷,借助AutoForm对材料为锌铝镁镀层板的某车型发动机罩外板拉深成形和回弹进行有限元仿真分析,根据零件的成形极限图、减薄率、起皱因子、主应变、次应变等结果优化了工艺参数,并分析了其拉深回弹,回弹量较小,对零件成形质量影响不大。研究表明,有限元分析可为锌铝镁涂层板的拉深成形及工艺参数优化提供参考,缩短了冲模制造周期,降低了零件开发与生产成本。