Most hulls of the ships are protected with paintings, sacrificial anode, and impressed current cathodic protection methods against corrosion problems. However, these conventional methods are not very effective because...Most hulls of the ships are protected with paintings, sacrificial anode, and impressed current cathodic protection methods against corrosion problems. However, these conventional methods are not very effective because the rudder of ships stern are exposed to very severe corrosive environment such as tides, speeds of ships, cavitations and erosion corrosion. The environmental factors such as cavitation and corrosion will cause damage for materials with the shock wave by the creation and destruction of bubble. To solve these problems, the cavitation and electrochemical experiments are executed for thermal spray coating with Al-Zn alloy wire material. Thereafter, and sealed specimens with F-Si sealer on Al-Zn alloy coated specimen are executed to improve electrochemical and anti-cavitation characteristics in sea water. The application of fluorine silicon sealing after spray coating of 15%Al-85%Zn seems to be appropriate not only in static environment but also in dynamic environment.展开更多
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 therm...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.展开更多
Abstract The mechanical properties of plasma-sprayed thermal barrier coating (TBC) play a vital role in governing their lifetime and performance. This work investigated the microstructural and mechanical properties ...Abstract The mechanical properties of plasma-sprayed thermal barrier coating (TBC) play a vital role in governing their lifetime and performance. This work investigated the microstructural and mechanical properties of TBC with high tem- perature treatment at 1 400℃ by scanning electron microscopy and indentation. We calculated elastic modulus and hardness through the application of Weibull statistics analysis. The results indicate that the microstructure of ceramic coat- ing will change continuously at high temperature, and accordingly the porosity decreases due to the grain growths and crack closes. In addition, the elastic mod- ulus and hardness nonlinearly go up with the heat treatment time and go down with increasing porosity. This demonstrates that the microstructural evolution and porosity of TBC are caused by high temperature treatment, and as a result its mechanical properties are influenced.展开更多
In this study,Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process.X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corro...In this study,Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process.X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corrosion products.Open circuit potential(OCP),electrochemical impedance spectroscopy,and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers(SAE)J2334 solution of varying durations.This solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited coatings.However,the Al–Mg alloy coating maintained an OCP of approximately-0.911 V versus Ag/Ag Cl in the SAE J2334 solution even after 792 h of exposure.This indicates that it protects the steel sacrificially,whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion products.The Al–Mg coating acts as a self-healing coating and provides protection by forming Mg_6Al_2(OH)_(16)CO_3(Al–Mg layered double hydroxides).Mg_6Al_2(OH)_(16)CO_3has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the coating.The presence of Zn in the corrosion products of the Al–Zn coating allows dissolution,but,at the same time,Zn_5(OH)_6(CO_3)_2and Zn_6Al_2(OH)_(16)CO_3are formed and act to reduce the corrosion rate.展开更多
Composition design of high-entropy carbides is a topic of great scientific interest for the hot-end parts in the aerospace field.A novel theoretical method through an inverse composition design route,i.e.initially ens...Composition design of high-entropy carbides is a topic of great scientific interest for the hot-end parts in the aerospace field.A novel theoretical method through an inverse composition design route,i.e.initially ensuring the oxide scale with excellent anti-ablation stability,is proposed to improve the ablation resistance of the highentropy carbide coatings.In this work,the(Hf_(0.36)Zr_(0.24)Ti_(0.1)Sc_(0.1)Y_(0.1)La_(0.1))C1-δ(HEC)coatings were prepared by the inverse design concept and verified by the ablation resistance experiment.The linear ablation rate of the HEC coatings is1.45μm/s,only 4.78%of the pristine HfC coatings after the oxyacetylene ablation at 4.18 MW/m2.The HEC possesses higher toughness with a higher Pugh's ratio of 1.55 in comparison with HfC(1.30).The in-situ formed dense(Hf_(0.36)Zr_(0.24)Ti_(0.1)Sc_(0.1)Y_(0.1)La_(0.1))O2-δoxide scale during ablation benefits to improve the anti-ablation performance attributed to its high structural adaptability with a lattice constant change not exceeding 0.19%at 2000-2300℃.The current investigation demonstrates the effectiveness of the inverse theoretical design,providing a novel optimization approach for ablation protection of high-entropy carbide coatings.展开更多
For corrosion protection of carbon steel in a marine environment,cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy wires.The surface hardness of Al and Al-Mg thermal spray coatings incr...For corrosion protection of carbon steel in a marine environment,cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy wires.The surface hardness of Al and Al-Mg thermal spray coatings increased with Mg content.And the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating layers.The Al and Al-Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential measurements.And an anodic polarization experiment revealed a tendency of activation polarization with no passivation.Furthermore,the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area,and the Al-3Mg thermal spray coating layer presented less surface damages than others.In addition,the Al-3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion protection.Therefore,it is an optimal thermal spray material for sacrificial anode.展开更多
The primary focus during surgery is to ensure successful implantation by achieving long-term and stable fixation of implants.Orthopaedic surgery is now more focused on the development of novel biomaterials intended to...The primary focus during surgery is to ensure successful implantation by achieving long-term and stable fixation of implants.Orthopaedic surgery is now more focused on the development of novel biomaterials intended to improve implant performance.To obtain a better understanding of metal implants,this article investigated the causes of material failures in certain cases and analysed a few case studies.The interaction between the implant and bone tissue was a crucial aspect of successful implantation,and this study explored the factors influencing this interaction as well as ways to improve it.Several modern approaches used for modifying implant surfaces were systematically illustrated and briefly analysed.Thermal spray coatings were often favoured because of their wide range of coating materials,but other substantial surface modifications(such as friction stir processing and laser surface texturing)were also used for a selection of applications.Notably,implant surfaces with desirable features,such as biocompatibility,antibacterial properties,corrosion resistance,and wear resistance,were essential for optimising implant functionality.This systematic review's main aim is to provide exhaustive reference information and a broad overview to advance the production and design of orthopaedic implants.展开更多
文摘Most hulls of the ships are protected with paintings, sacrificial anode, and impressed current cathodic protection methods against corrosion problems. However, these conventional methods are not very effective because the rudder of ships stern are exposed to very severe corrosive environment such as tides, speeds of ships, cavitations and erosion corrosion. The environmental factors such as cavitation and corrosion will cause damage for materials with the shock wave by the creation and destruction of bubble. To solve these problems, the cavitation and electrochemical experiments are executed for thermal spray coating with Al-Zn alloy wire material. Thereafter, and sealed specimens with F-Si sealer on Al-Zn alloy coated specimen are executed to improve electrochemical and anti-cavitation characteristics in sea water. The application of fluorine silicon sealing after spray coating of 15%Al-85%Zn seems to be appropriate not only in static environment but also in dynamic environment.
基金Project supported by the Ministry of Education,Science Technology(MEST) and Korea Industrial Technology Foundation(KOTEF) through the Human Resource Training Project for Regional Innovation
文摘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.
基金supported by the National Natural Science Foundation of China(91216301,11172151,11232008,and 11372118)the Specialized Research of Tsinghua University Initiative Scientific Research Program
文摘Abstract The mechanical properties of plasma-sprayed thermal barrier coating (TBC) play a vital role in governing their lifetime and performance. This work investigated the microstructural and mechanical properties of TBC with high tem- perature treatment at 1 400℃ by scanning electron microscopy and indentation. We calculated elastic modulus and hardness through the application of Weibull statistics analysis. The results indicate that the microstructure of ceramic coat- ing will change continuously at high temperature, and accordingly the porosity decreases due to the grain growths and crack closes. In addition, the elastic mod- ulus and hardness nonlinearly go up with the heat treatment time and go down with increasing porosity. This demonstrates that the microstructural evolution and porosity of TBC are caused by high temperature treatment, and as a result its mechanical properties are influenced.
基金supported by the research fund of Hanyang University (No. HY-2014-P)
文摘In this study,Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process.X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corrosion products.Open circuit potential(OCP),electrochemical impedance spectroscopy,and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers(SAE)J2334 solution of varying durations.This solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited coatings.However,the Al–Mg alloy coating maintained an OCP of approximately-0.911 V versus Ag/Ag Cl in the SAE J2334 solution even after 792 h of exposure.This indicates that it protects the steel sacrificially,whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion products.The Al–Mg coating acts as a self-healing coating and provides protection by forming Mg_6Al_2(OH)_(16)CO_3(Al–Mg layered double hydroxides).Mg_6Al_2(OH)_(16)CO_3has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the coating.The presence of Zn in the corrosion products of the Al–Zn coating allows dissolution,but,at the same time,Zn_5(OH)_6(CO_3)_2and Zn_6Al_2(OH)_(16)CO_3are formed and act to reduce the corrosion rate.
基金supported by the National Key R&D Program of China(2022YFB3708600,2021YFA0715802)Aeronautical Science Foundation of China(2022Z055053004)+1 种基金Fund of Key Laboratory of National Defense Science and Technology(WDZC20235250505)National Major Science and Technology Projects of China(J2022-VI-0011-0042).
文摘Composition design of high-entropy carbides is a topic of great scientific interest for the hot-end parts in the aerospace field.A novel theoretical method through an inverse composition design route,i.e.initially ensuring the oxide scale with excellent anti-ablation stability,is proposed to improve the ablation resistance of the highentropy carbide coatings.In this work,the(Hf_(0.36)Zr_(0.24)Ti_(0.1)Sc_(0.1)Y_(0.1)La_(0.1))C1-δ(HEC)coatings were prepared by the inverse design concept and verified by the ablation resistance experiment.The linear ablation rate of the HEC coatings is1.45μm/s,only 4.78%of the pristine HfC coatings after the oxyacetylene ablation at 4.18 MW/m2.The HEC possesses higher toughness with a higher Pugh's ratio of 1.55 in comparison with HfC(1.30).The in-situ formed dense(Hf_(0.36)Zr_(0.24)Ti_(0.1)Sc_(0.1)Y_(0.1)La_(0.1))O2-δoxide scale during ablation benefits to improve the anti-ablation performance attributed to its high structural adaptability with a lattice constant change not exceeding 0.19%at 2000-2300℃.The current investigation demonstrates the effectiveness of the inverse theoretical design,providing a novel optimization approach for ablation protection of high-entropy carbide coatings.
基金a part of the project titled "Construction of eco-friendly Al ship with painting,and maintenance/repairment free," funded by the Ministry of Oceans and Fisheries,Korea
文摘For corrosion protection of carbon steel in a marine environment,cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy wires.The surface hardness of Al and Al-Mg thermal spray coatings increased with Mg content.And the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating layers.The Al and Al-Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential measurements.And an anodic polarization experiment revealed a tendency of activation polarization with no passivation.Furthermore,the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area,and the Al-3Mg thermal spray coating layer presented less surface damages than others.In addition,the Al-3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion protection.Therefore,it is an optimal thermal spray material for sacrificial anode.
基金J Sharath Kumar thanks to Ministry of Education,Government of India for the research scholarship.
文摘The primary focus during surgery is to ensure successful implantation by achieving long-term and stable fixation of implants.Orthopaedic surgery is now more focused on the development of novel biomaterials intended to improve implant performance.To obtain a better understanding of metal implants,this article investigated the causes of material failures in certain cases and analysed a few case studies.The interaction between the implant and bone tissue was a crucial aspect of successful implantation,and this study explored the factors influencing this interaction as well as ways to improve it.Several modern approaches used for modifying implant surfaces were systematically illustrated and briefly analysed.Thermal spray coatings were often favoured because of their wide range of coating materials,but other substantial surface modifications(such as friction stir processing and laser surface texturing)were also used for a selection of applications.Notably,implant surfaces with desirable features,such as biocompatibility,antibacterial properties,corrosion resistance,and wear resistance,were essential for optimising implant functionality.This systematic review's main aim is to provide exhaustive reference information and a broad overview to advance the production and design of orthopaedic implants.