Research Of Nano Composite Electroforming

Electroforming is a nontraditional machining technology, in which a metallic part is produced by the electrodeposition of metal onto a cathode mandrel in the electrolytic bath. Many attention has been paid to it because of its'high fidelity of shape reproduction, cutting force-free, and no tool wear. Electroforming is now employed in many areas, such as aviation, aerospace, weapon, microelectromechanical system and so on.The nano composite electroforming is a kind of technique in which nano particles are suspended in the electrolyte and embedded in the growing metal layer. The well dispersed nano particles in a metal matrix do not only enhance the mechanical properties including wear and corrosion resistance, but also open up potential applications of the composite materials in microdevices. Recently, a considerable amount of research effort has been spent on electroforming of nanostructured composite, and many parts, such as micro-, mold, and electrode used in electrodischarge machining, have been prepared by using nano composite electroforming.Both the metal electrocrystallization theory and the codeposition mechanisms were reviewed in this dissertation. The influence of current density, nano particles concentration in the suspension, stir rate, and temperature of the bath on the nano particles inclusion into the deposit was studied, and the nano particles-metal composite layers were obtained with high weight percent of nano particles and uniform dispersion of nano particles. The morphology, component, and microstructure of nano composite electroforming layers were examined. In addition, the micro hardness, wear resistance, corrosion resistance, oxidation resistance, and magnetic properties of the nano composite layers were also evaluated.The following work has been finished in this dissertation:1. The nano composite electroforming technology with the aid of ultrasonic vibration was present to inhibit the agglomeration of nano particles in the nano composite layers. The experiments about the technology have been carried out, and its'feasibility was confirmed.2. The effect of electroforming parameters on the weight percent of CeO₂ nano particles, morphology, and the preferred orientation of the Ni-CeO₂ composite layers was investigated, and the experiments'results indicated that both the current density and the CeO₂ particles concentration in the suspension play a major role in the Ni-CeO₂ composite electroforming. The Ni-CeO₂ composite layer with high weight percent of CeO₂ inclusion into the layer might be acquired by using the optimized parameters.3. The influence of electroforming parameters on the micro hardness, wear resistance, corrosion resistance, and oxidation resistance of the Ni-CeO₂ nano composite layers were also examined. The experiments'results showed that the micro hardness of layer increased with the increment of weight percent of CeO₂ inclusion into the layer, and the wear resistance, corrosion resistance, and oxidation resistance of the composite layer were also enlarged while the weight percent of CeO₂ inclusion into the layer rose from 0 to 4.02%. However, the micro cracks occurred at the 4.98% weight percent of CeO₂ inclusion into the layer, which led to poor wear resistance, corrosion resistance, and oxidation resistance.4. The influence of both BaFe₁₂O₁₉ nano particles concentration and current density on the CoNi-BaFe₁₂O₁₉ composite deposit compositions have been investigated, respectively. The introduction of BaFe₁₂O₁₉ nano particles into the composite layers could prohibit the anomalous codeposition of Co-Ni alloy.5. The magnetic field was introduced to electroform the magnetic particles- ferromagnetic matrix composites. The effect of both BaFe₁₂O₁₉ nano particles concentration and current density on the CoNi-BaFe₁₂O₁₉ composite deposit compositions has been evaluated, and the experiments'result demonstrated that the high BaFe₁₂O₁₉ nano particles percent could be acquired by using a magnetic field.6. The maximum magnetic energy density, coercivity, and remanence of the CoNi-BaFe₁₂O₁₉ composite layers were investigated produced by nano composite electroforming with and without a magnetic field. With proper choice of electroforming parameters, the CoNi-BaFe₁₂O₁₉ composite layer with the maximum magnetic energy density 3.09 KJ/m3 could be fabricated without a magnetic field, and one with the maximum magnetic energy density 4.14 KJ/m3 might be prepared in the presence of a magnetic field.