| As a key component of battery, shell materials have great effect on the storageperformance, safety and electrical property of battery. In order to find a method toproduce pre-electroless nickel plating for steel battery shell, which is suitable for thequalified battery cases practically, continuously and rapidly, we focused on preparingmultilayer nickel cobalt alloy coatings on steel strip by the way of electro-deposit,heat treatment and cold rolling. And put them into small lot production. Differentkinds of batteries were made by battery steel shells which were prepared by differentpreparation technologies. The properties of all specimens were studied. The detailedworks in this dissertation include:(1) By using the base material of the punching cold rolling carbon structural steel,5kinds of cobalt nickel plated steel belt have been prepared through electroplating,bell type heat treatment, continuous heat treatment and smooth process. With the testmethod of XRD, SEM and EDS, we characterized the microstructure of the5kinds ofcobalt nickel plated steel belt. The result showed that a Ni/Co/Fe alloy layer wasformed between the coating surface and substrate with (111)(200) double preferredstructures. No other textures were found clearly after heat treatment and cold rolling.With the method of bell type heat treatment and continuous heat treatment, the formedNi/Co/Fe alloy layer between plating nickel cobalt steel belt and substrate were2.5μmand0.5μm, respectively.4%smoothing process could achieve the effect of smoothcoating.(2) The comprehensive corrosion resistance of different preparation cobalt nickelplated steel belts and the stamping forming of steel battery shells were tested by saltspray testing machine, copper sulfate spot test and so forth. Results showed that thecorrosion potential of the cobalt nickel plated steel dealt by the bell type heattreatment and the formation process was the most positive, which was-0.243V. Theporosity of the sample was less than others. When the test system was10%NaOH inthe alkaline solution, the passivation zone was the widest and the transfer resistancewas the largest, which were459.1mV and2920Ω·cm~2, respectively. Under thiscondition, the samples showed good corrosion resistance. The corrosion resistance ofbattery shell formed by stamping was the best. The mechanical performance of cobaltnickel plated steel belt prepared by different preparations was tested. Results indicated that the bell type heat treatment and continuous heat treatment made the hardness ofthe samples decreased, while smoothing process increased the hardness of the samples.The yield strength of samples dealt by continuous heat treatment and smoothingprocess kept in0.659, and the elongation was38.5%. The surface roughness beforeand after the tensile were minimum.(3) The stamping property of the5kinds of cobalt nickel plated steel belt wascharacterized. The results showed that stamping speed of the cobalt nickel plated steelbelt prepared by the continuous heat treatment and smoothing process reaches160/min. The crack was less, and3h Nss experiment reaches9grade. Using the sameraw materials and technological conditions, five kinds of batteries were made bybattery steel shell which was prepared by five different preparation technologiesthrough the continuous production line for LR6alkaline manganese cell. And theperformance of battery safety, high temperature and high humidity, the leakage andbattery electrical performance were all tested. Results showed that the Ni-Co coatingwhich prepared by combining the electroplating, continuous heat treatment andsmoothing process had excellent uniformity, storage performance and electricalproperty when assembled to battery.In a word, the Ni-Co coating prepared by combining the electroplating,continuous heat treatment and smoothing process has excellent uniformity, andsatisfies the decay resistance, safety and storage performance of high performancebatteries, and it is suitable for industry. |
PDF Full Text Request