1. 研究目的与意义（文献综述包含参考文献）
文 献 综 述Aeroengine has been a highly complex mechanism, especially for engineers to reproducethese aero parts perfectly and efficiently, it was a tough and near impossible challenge to overcome. Yet engineers manage to come up with new and generation leaping changes to strengthen the processing machine over and over again, providing the world with new thought evolving our conventional device into a futuristic machine. Small changes on machines comes impactful outcomes. The electrochemical deposition has been part of aeroengine for generations, every evolution of electrochemical deposition is the knowledge of the previous biggest inventor respected by the people around. Every evolution made on the machine will affect the stability, efficiency, economics and even the quality of the aeroengine made. Conventional electrochemical depositionA simple electrochemical plating system is shown schematically in Figure 1. The voltage/current source and the electrodes, anode and cathode, are submerged in the electrolyte or plating bath in the electro part of the system, with the circuit completed by the movement of ions from the plating bath to the electrodes in the chemical part of the system. The metal to be deposited may be the anode, which would be ionised and dissolve in the electrolyte, or it could originate from the plating bath's composition. Anodes provide copper, tin, silver, and nickel metal, while gold salts are introduced to the plating bath in a regulated procedure to maintain the bath's composition. Other ions are usually present in the plating bath to aid current passage between the electrodes. The cathode is the location where metal is deposited. The following is the order in which the plating process takes place:1. The cathode receives electrons from the power supply.2. The reduced metal plates onto the cathode after an electron from the cathode transfers to a positively charged metal ion in the solution.3. The circuit to the anode is completed by ionic conduction through the plating bath.4. Depending on whether the anode material is soluble, the source of the metal to be plated, or insoluble, inert, two separate processes occur at the anode. If the anode material is soluble, an electron is given up and a positively charged metal ion enters the solution, replenishing the metal content of the plating bath. A negatively charged ion from the plating bath gives up an electron to the anode if the anode is inert. 5. The electron passes from the anode to the power supply, completing the circuit. Because metal deposition at the cathode requires an electron, the rate of deposition is limited.Fig-1. The flow of electrons, or the current flowing from the rectifier, is required for electrochemical plating. As a result, the thickness of the deposit is determined by the current and the length of time it is applied. This is due to Faraday's law, which states that the weight of a substance created during electrolysis by an anode or cathode electrode reaction is directly proportionate to the amount of electricity passing through the cell.If the metal deposition is localised to form small and shaped electrodes directly, electrochemical deposition is a promising technology for fabricating high-aspect-ratio microtools of various materials. This technology has been discovered to be one of the most straightforward and cost-effective methods of fabricating microelectrodes for micromachining applications.The history of Electrochemical deposition (ECD), also known as electrodeposition, electroplating, or electrolytic deposition, is a surface modification technique in which a thin and tightly adherent coating of metal, oxide, salt, or macromolecule is deposited onto a conducting substrate through simple electrolysis of a solution containing a desired substance. Electrochemical deposition can be traced back to the year 1800 where a chemist known as Alessandro Volta invented the electrical battery. In, 1905 by a chemist by the name Tafel then enhanced the concept into a new concept known as concept of overpotential. Erdey-Gruz and Volmer (currentpotential relationship, 1930) then used the basic of Tafel and converting it using the potential different with the help of electricity, the history then follows by Eyring and Wynne-Jones (formulation of absolute rate theory, 1935), Lorenz (consideration of rate-determining surface diffusion of adions, 1954), Conway and Bockris (calculation of probabilities of charge transfer to different sites on the metal surface,1958), and Dickson perfected the whole experiment by calculation of probabilities of charge transfer to (study of nucleation and growth of electrodeposited gold on surfaces of silver, 1965. The use of electrochemical deposition in the creation of nano-coatings has become a hot topic, advancing nanomaterial synthesis from the lab to the real world. Rapidity, low costs, high purity of products, high deposition rates, homogeneous distribution of particles, ease of process control, variability of coating composition, sustainability for complex substrate geometries, reduced waste materials, and the ability to process continuously are all advantages of this century-old process. Furthermore, it is feasible to generate coatings with customised morphology and structures by manipulating ECD variables such as starting pH, electrolyte composition, current density, deposition duration, and reaction temperature. ECD has been successfully used to produce coatings with varied degrees of crystallinity under milder temperatures and faster reaction periods than any other approach. The ECD method can only be used on electrically conducting materials such metals, alloys, semiconductors, electrically conductive polymers, and oxides. The research and production of magnetic thin films is a typical application of ECD . The efficiency of this technology is based on its low prices, high throughput, and good deposit quality - features that are advantageous in the magnetic recording sector, such as the formation of Permalloy films. Microelectrochemical systems (MEMS) and devices such as sensors, micro actuators, micromotors, and frictionless micro gears are among the most common applications of magnetic films. These materials have been effectively employed in the fabrication of magnetic recording head devices; the simplicity with which ECD can produce precise structures allows for an increase in the areal recording density.ECD is a critical technique in the fabrication of precious metal coatings. Antimicrobially active coatings, precious metal catalyst, and corrosion protective layers are only a few of the applications for this type of deposit. By customizing operating parameters such as temperature, pH, and current density, the ECD process's high controllability allows the fabrication of many types of deposit structures with predetermined parameters. Figure 3 depicts the reduction pathway of a simple solvated metal salt. The migration of a solvated ion present in the electrolyte (a) to the cathode, where it enters the diffusion layer, is caused by current from an external source travelling through an electrochemical cell, as well as diffusion and convection mechanisms (b). The electrical field in the diffusion layer is strong enough to align solvating water molecules but weak enough to prevent free metal ions from being liberated. The solvating water molecules are removed from the solvated metal ion when it reaches the Helmholtz layer (c), leaving free metal ion. Finally, the metal ion is reduced on the cathode surface, resulting in the formation of a metal deposit. The diagrams show (a) bulk electrolyte (b) diffusion layer (c) Helmholtz layerElectrochemical polymerization, a process that results in the production of conducting polymer coatings, is a specific example of ECD. The anodic oxidation of monomer contained in electrolytic solution occurs at the surface of the working electrode during the electro polymerization process. The creation of a radical cation (polaron) in the first stage, followed by a chemical pairing reaction between two radical cations in the second step, results in the formation of dilation (bi-polaron). The procedure is repeated until the oligomer produced is insoluble in solvent and precipitates on the anode surface. The electrochemical polymerization of pyrrole is depicted in a schematic diagram. The advantages of electrochemical polymerization include the easiness of the control of film thickness, direct grafting of polymer onto the electrode surface as well as possibility to perform in situ characterization of the growing polymer with the use of electrochemical and/or spectroscopic methods. Conducting polymers are versatile materials that are successfully used in a variety of applications. Polyaniline coatings are found to exhibit excellent corrosion resistance, even in aggressive environments, polypyrrole and its derivatives are applied as biocompatible coatings in biomedical engineering, while poly(3,4-ethylenedioxythiophene) can be utilized in photovoltaic and electrochromic devices. Apart from classical electrodeposition process, there are numerous alternatives of this technique appearing in the literature. One of them is ultrasound assisted electrodeposition. Ultrasounds are recognized to induce strong physical, chemical and mechanical changes that are able to activate chemical and electrochemical reactions. That is why extensive 8 research has been conducted in order to couple an ultrasound field with an electric field. This technique was successfully applied in a process of fabrication of TiO2 nanotube array/CdSe nanoparticle/TiO2 composite, making CdSe nanoparticles prone to disperse into the nanotube arrays.3D microstructures3D microstructures could be easily fabricated on high-strength metals using this method. Nonconductive masking is used to achieve electrochemical deposition in a predetermined and controlled area. If a sufficient amount of electric current passes through the electrolyte solution, the metallic ion can become solid metal and deposit on the cathode surface. The electrolyte is made up of charged ions that are formed when a metallic salt is dissolved in water. As an electrolyte, an anode is immersed in an acidic metallic salt solution.Above the anode is the cathode, which is then deposited electrode. To create a complex shape of deposition, a non-conductive mask is placed between the anode and the cathode. During deposition, a small constant gap is maintained between the anode and the mask. Metal ions are deposited on the cathode when a current passes through the non-conductive mask. By properly designing the mask pattern, deposition can be localised to create the desired micro-shape and size of the 3D microstructure on the cathode. The mask is made of a non-conductive material such as polymethyl methacrylate and can be machined into various cross-sectional shapes using various precision micromachining techniques. For effective deposition localization, a pulse-type voltage is used. Different process parameters such as applied voltage, pulse frequency, duty ratio, and the gap between electrodes and the mask can be controlled to control the porosity and accuracy of the electrochemically deposited structure of the microtool. Figure 6.15 shows multimicroelectrodes fabricated by electrochemical depositions with an array mask, which can speed up the manufacturing process. Localized electrochemical deposition is a fantastic way to make complex cross-sectional microelectrodes quickly and easily. Microtools and microfeatures made of metals, metal alloys, conductive polymers, and semiconductors can be successfully fabricated using this method for a variety of applications. Nickel microstructures have been constructed and the notion of localised electrochemical deposition has been demonstrated. By limiting the area of the electric field, electrodeposition is spatially limited, resulting in deposit localization. Polycrystalline nickel is electrodeposited at two orders of magnitude faster rates than traditional electroforming, owing to local convection caused by intense bubble formation. Fabricated Structures include a multi-coiled helical spring and a loo-pm-high, 10-pm-diameter column. Results from two-dimensional selective electrodeposition processes suggest that 3-D electro-deposition with submicrometer spatial resolution is feasibleThe biggest advantage of electrochemical deposition or ECD in short is the economical and environmentally-friend method of protecting and embellishing metal substrates. High productivity. E-coatings have a number of advantages, one of which is their great efficiency. An even film is put to the whole surface throughout this technique, including places that are twisted and hence difficult to access. The necessity for reworking is reduced, and the risk of scrap is reduced. In addition, when compared to spray spraying, electrodeposition coating results in substantially less paint loss. Environmental compatibility has been improved.In compared to other coating techniques, electrodeposition coatings put less strain on the environment, such as due to solvent vapours. Additionally, the pressure on personnel is greatly reduced. ECD is unique, that energy-efficient electrodeposition coatings has also made waves. These allow for reduced baking temperatures of up to 30 degrees, resulting in significant energy savings. The combination of a flawless finish and very effective protection is unbeatable. Control cabinets, control panels, computer casings, and other related goods are good examples of e-coating applications. These safeguard important technology in computer systems or telecommunications centres, for example, and are critical components in the operation of entire production systems. ECD coatings provide such casings a high-tech finish that matches their contents. Furthermore, fashionable or customised designs are commonly desired. Multi-layer coating systems with electrodeposition coating whether as liquid or powder coatings are always the best option. You'll get not just the highest protection and performance, but also a smooth, fine-structured, or coarse finish, depending on your preferences.Electrochemical approaches have proven to be effective in the creation of nanocoating, Corrosion protection, biomedical engineering, fuel cells, supercapacitors, and photovoltaic and electrochromic devices are just a few of the applications where theyve proved effective. The ongoing development of fresh tactics as an alternative to the qualities of the resulting coatings can be precisely controlled using well-known methods. making Mechanical and electrochemistry unstoppable technology for the production of a wide range of sophisticated materials.
2. 研究的基本内容、问题解决措施及方案
本课题需要解决的问题: The key parts of aeroengine need to be coated and manufactured by electrochemical deposition, and the selected materials have complex shapes and high performance requirements, so the manufacturing technology is facing severe challenges. The high precision and high surface quality preparation technology of aerospace materials has become a hot research topic in scientific and engineering fields at home and abroad.拟采用的解决方案:1. By increasing increasing the current input into the machine under a control environment will helps ionizing a stronger material which has higher ionizing energy such as titanium.2. Having multiple axis wielding header to increase the efficiency and without the need to turn the material over and over.
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