本文選題：Ni-Co-P　切入點(diǎn)：脈沖技術(shù)　出處：《沈陽理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鎳基合金直流電鍍以其鍍液穩(wěn)定、易于控制和制備出的合金鍍層性能優(yōu)良而成為研究的熱點(diǎn),盡管直流電沉積對合金鍍層的結(jié)晶細(xì)化、鍍層硬度、耐蝕性的提高有明顯的作用,但是通過國內(nèi)外學(xué)者的長期、大量研究后,直流電沉積對鍍層的結(jié)晶細(xì)化、鍍層硬度的提高已接近極限。選擇新的電沉積制備復(fù)合鍍層方式成為必然--用脈沖技術(shù)取代傳統(tǒng)的直流復(fù)合電沉積是可預(yù)見的有效方式。本文以Ni-Co-P合金鍍層為研究對象,采用直流電鍍、單脈沖電鍍、周期換向脈沖電鍍技術(shù)制備Ni-Co-P合金鍍層。通過極化曲線、電化學(xué)阻抗譜測試合金鍍層的耐蝕性,采用硬度儀測試合金鍍層的硬度,采用SEM圖譜分析了各合金鍍層的微觀形貌,通過EDAX和XRD分析了各合金鍍層的元素組成和相組成。研究表明:Ni-Co-P直流合金鍍層最佳工藝:硫酸鎳:250g/L、氯化鎳:40g/L、七水合硫酸鈷:25g/L、次亞磷酸鈉為:4g/L、硼酸:35g/L、SDS:0.1g/L、電鍍密度:5A/dm2、溫度:50℃、pH:3.5-4.5、t:30min。合金鍍層的性能最好,硬度為629HV(200gf),腐蝕電流為9.56μA,線性極化電阻為4377ohm。Ni-Co-P合金單脈沖鍍層最佳工藝:硫酸鎳:250g/L,氯化鎳:40g/L,七水合硫酸鈷:25g/L,次亞磷酸鈉:4g/L,硼酸:35g/L,SDS:0.1g/L,溫度:50℃,pH:3.5-4.5,t:30min,正占空比為80%,正向平均電流密度為4A/dm2,脈沖頻率為1KHz。Ni-Co-P合金單脈沖鍍層的硬度為675HV(50gf),腐蝕電流為17.9μA,線性極化電阻為2407ohm。結(jié)晶度為69.23%,微粒直徑為20.92nm;Ni-Co-P合金周期換向脈沖電鍍最佳工藝:硫酸鎳:250g/L,氯化鎳:40g/L,七水合硫酸鈷:25g/L,次亞磷酸鈉:4g/L,硼酸:35g/L,SDS:0.1g/L,溫度:50℃,pH:3.5-4.5,T:30min,正占空比為80%,正向平均電流密度為4A/dm2,脈沖頻率為1KHz,負(fù)占空比為8%,負(fù)電流密度為0.3A/dm2。Ni-Co-P合金周期換向脈沖鍍層硬度為523HV(50gf),腐蝕電流為15.8μA,線性極化電阻為2535ohm,結(jié)晶度為91.64%,微粒直徑為22.76nm。確定最佳熱處理工藝為:熱處理溫度為300℃、熱處理時(shí)間為120min。最佳熱處理工藝下的Ni-Co-P合金鍍層的硬度達(dá)到708HV(50gf)、自腐蝕電流為5.10μA,線性極化電阻為3818ohm。晶粒尺寸27.07nm,結(jié)晶度為95.53%。最佳的Ni-Co-P合金脈沖鍍液中硝酸鈰的添加量為0.3g/L,并對最佳硝酸鈰添加量的Ni-Co-P合金脈沖鍍層測試,硬度達(dá)到502HV(50gf),Ni-Co-P合金鍍層結(jié)晶度最大,為91.74%
[Abstract]:Direct current electroplating of nickel-based alloy has become a hot research area because of its stable bath, easy to control and excellent properties of alloy coating, although DC electrodeposition plays an important role in improving the crystallization, hardness and corrosion resistance of the alloy coating. However, after a long period of research by scholars at home and abroad, the crystallization of the coating was refined by direct current electrodeposition. The hardness of the coating is near the limit. It is inevitable to choose a new electrodeposition method to prepare the composite coating. It is a predictable and effective way to replace the traditional DC composite electrodeposition with pulse technique. In this paper, the Ni-Co-P alloy coating is taken as the research object. The Ni-Co-P alloy coating was prepared by DC electroplating, monopulse electroplating and periodic commutation pulse electroplating. The corrosion resistance of the alloy coating was measured by polarization curve and electrochemical impedance spectroscopy, and the hardness of the alloy coating was measured by hardness tester. The microstructure of the alloy coatings was analyzed by SEM. The element composition and phase composition of each alloy coating were analyzed by EDAX and XRD. The results show that the optimum process of the alloy coating is: nickel sulfate: 250g / L, nickel chloride: 40g / L, cobalt sulfate heptahydrate: 25g / L, sodium hypophosphite: 1 / 4g / L, sodium borate: 35g / L SDSW 0.1 g / L, electroplating density: 5Ar / m2, temperature. The alloy coating has the best properties. Hardness 629HVN 200gfN, corrosion current 9.56 渭 A, linear polarization resistance 4377ohm.Ni-Co-P alloy monopulse coating: nickel sulfate: 250g / L, nickel chloride: 40g / L, heptahydrate cobalt sulfate: 25g / L, sodium hypophosphite: 4g / L, boric acid: 35g / L SDS: 0.1g / L, temperature: 50 鈩，

本文編號(hào)：1576941