Study On Dissolving Agent Of Nickel-Based Single Crystal Superalloy And Its Milling Ability

In order to reduce costs,resource diversification is the development trend of nickel electrolysis refining.The raw materials for the production of metal nickel are mainly derived from the smelting of minerals,but the recovery of nickel alloys has gradually become a part of its resources.The waste aircraft engine blade nickel-based single crystal superalloy contains more than 50%nickel and can be recovered as a better nickel resource.Due to the loss of valuable elements in the pyrometallurgical process,researchers have been working hard to develop wet processes to reduce the loss of valuable elements.In this thesis,the waste aircraft engine blades DD5 and DD6 nickel-based single crystal superalloys are used as resources for wet treatment and recovery,and the solution and its milling ability are studied.In this paper,the DD5 nickel-based single crystal superalloy blades of waste aircraft engine blades were firstly studied in the four non-nickel-based single crystal alloy solutions of H2SO4-H2O2,H2SO4-H2O2-ethylene glycol,H2SO4-Fe2(SO4)3 and H2SO4-FeCl3.The dissolution effect was characterized by metallographic microscope,scanning electron microscope,atomic force microscope,etc.,and the dissolution rate of each solution was measured by the weight loss method.Based on this,H2SO4-FeCl3-MnO2 solution and H2SO4-FeCl3-MnO2-TEOS-Glycerol milling paste for DD5 and DD6 nickel-based single crystal superalloy blade milling were developed.The research found that:(1)The ability of traditional four solutions to dissolve DD5 nickel-based single crystal superalloy blades is H2SO4-H2O2<H2SO4-H2O2-ethylene glycol<H2SO4-Fe2(SO4)3<H2SO4-FeCl3;H2SO4-FeCl3 is the best solution for DD5 nickel-based single crystal superalloy,in which the concentration of H2SO4 is about 4.8mol·L-1,and the concentration of FeCl3 is about 0.16mol·L-1.(2)Based on this,Developed H2SO4-FeCl3-MnO2 dissolving agent with better solubility of DD5 and DD6 alloy single crystal blades than H2SO4-FeCl3.The amount of MnO2 added is 1g·L-1.The process research shows that the primary and secondary factors affecting the solvency of DD5 and DD6 single crystal blades are temperature>time>H2SO4:FeCl3>MnO2 addition;the suitable dissolution conditions are temperature 50℃ and time 3h,at which time the alloy has the fastest dissolution rate.(3)H2SO4-FeCl3-MnO2-TEOS-Glycerol milling paste was developed for the removal of local stress layer of nickel-base single crystal superalloy blades,which can play the role of localized milling.The suitable milling condition is that the temperature is 50℃ and the time is 4h.Under this condition,the surface roughness of the DD5 and DD6 alloy single crystal blades after milling is small and the integrity is good.