【作者】 王丽；

【导师】 王立娟；

【作者基本信息】 东北林业大学 ， 林产化学加工工程， 2016， 博士

【摘要】 木材是一种天然的有机高分子材料,虽然其本身具有质轻、可再生等优异特性,但由于木材本身不具有导电性能,因此,在很多应用领域存在局限性。在木材表面赋予层金属膜是拓展木材应用领域的重要途径之一,其中,使木材表面得以金属化修饰最有效的方法就是化学镀。虽然近几年木材表面化学镀研究进展迅速,但多以铜或二元合金为主,达到了木材与金属复合的目的,赋予材料以新的性能,但铜或二元合金存在耐腐蚀性差等缺点,限制了材料的长久应用。因此,开展木材表面化学镀耐腐蚀的镍基三元合金是提高腐蚀性的重要手段。本论文以非洲白梧桐、桦木为基材,以镀层表面的金属沉积率和电阻率为参考值,研究镍基三元合金化学镀镀液的组成,对镀层特性进行分析、表征和性能测试。研究结果如下：(1)以非洲白梧桐单板为基材,以次亚磷酸钠为还原剂,经硅烷前处理的木材表面化学镀Ni-Fe-P三元合金,获得较优前处理条件如下：陈化5h的1.5%的硅烷溶液处理后,于20 mL氯化钯溶液处理10 min,最后在2 g/L次亚磷酸钠溶液中处理10min；适宜的镀液组成及其操作工艺条件如下：硫酸镍45 g/L,硫酸亚铁铵17.5 g/L,次亚磷酸钠27.5 g/L,酒石酸钾钠70 g/L,硫酸铵40 g/L,pH值9.2,施镀时间40 min,施镀温度90℃。电磁屏蔽效能测试表明,镀后单板的电磁屏蔽效能达到45 dB以上,较非洲白梧桐素材有显著提高；VSM测试表明,镀层具有优良的磁学性能；SEM测试得到,镀后的非洲白梧桐单板表面完全被金属镀层所覆盖,镀层均匀、连续、有光泽,并仍具有木材的纹理特征。XPS和EDS测试表明,镀层中含有Ni、Fe和P三种元素,其中Ni为主要成分,含量高达92.51%,Fe和P的含量相对较少,分别为5.57%和1.92%；XRD测试表明,Ni-Fe-P三元合金镀层呈晶态结构；结合强度测试中镀层与木材没有完全分离,表明Ni-Fe-P合金镀层与木材表面结合强度较高；镀后单板的初始接触角为104°,15 s后接触角仅下降了6°,单板表面由镀前的亲水性转变为镀后的疏水性；Ni-Fe-P三元合金镀层的腐蚀电位为-0.301 V,腐蚀电流为密度为7.58×10-6A/cm2,腐蚀阻抗为3652.9Ω/cm2,耐腐蚀性明显高于Ni-P二元合金。以硼氢化钾碱性溶液对非洲白梧桐单板进行前处理的最佳的前处理工艺如下：硼氢化钾4 g/L,氢氧化钠3 g/L,处理时间8 min；此法的适宜镀液和施镀工艺条件如下：硫酸镍45g/L,硫酸亚铁铵17.5 g/L,次亚磷酸钠25 g/L,酒石酸钾钠70 g/L,硫酸铵25 g/L,pH值9.4,施镀时间60 min,施镀温度90℃；电磁屏蔽效能测试表明,镀后单板的电磁屏蔽效能达到50 dB以上,成功获得木质电磁屏蔽材料；VSM测试表明,镀层具有优良的磁学性能；SEM测试得到,镀后的非洲白梧桐单板表面完全被金属镀层所覆盖,镀层均匀、连续、有光泽,并保留了木材原有的孔隙结构。XPS和EDS测试表明,镀层中含有Ni、Fe和P三种元素,其中Ni为主要成分,含量高达93.60%,Fe和P的含量相对较少,分别为4.71%和1.69%。XRD测试表明,Ni-Fe-P三元合金镀层呈晶态结构；结合强度测试中镀层与木材没有完全分离,说明Ni-Fe-P合金镀层与木材表面结合强度较高；镀后单板的初始接触角为110°,15 s后接触角仅下降了2°,单板表面由镀前的亲水性转变为镀后的疏水性；Ni-Fe-P三元合金镀层的腐蚀电位为-0.3610 V,腐蚀电流为密度为7.89×10-6A/cm2,腐蚀阻抗为4160.9Ω/cm2,此法获得的镀层具有比较好的耐腐蚀性。(2)以桦木单板为基材,采用非钯活化工艺进行Ni-W-P三元合金化学镀。所得化学镀Ni-W-P三元合金的较优镀液及其工艺如下：硫酸镍22.5 g/L,钨酸钠17.5 g/L,次亚磷酸钠27.5 g/L,柠檬酸钠25 g/L,乳酸5 g/L,氯化铵30 g/L,pH值8.8,施镀温度88℃,施镀时间40 mmin；XPS和EDS测试表明,镀层含有Ni、W和P三种元素,Ni为主要成分,含量高达89.80%,W和P的含量相对较少,分别为4.48%和5.72%。；XRD测试表明,Ni-W-P三元合金镀层属于微晶态结构；SEM测试得到,镀后的桦木单板表面镀层覆盖均匀,具有金属光泽,同时也保留了木材本身的纹理特征；磁屏蔽效能测试表明,镀后单板的电磁屏蔽效能达到40 dB以上；结合强度测试中镀层与木材没有完全分离,说明Ni-W-P合金镀层与木材表面结合牢固；镀后单板的初始接触角为119°,15 s后接触角仅下降了2°,单板表面由镀前的亲水性转变为镀后的疏水性；Ni-W-P三元合金镀层的腐蚀电位为-0.3400 V,腐蚀电流为密度为2.163×10-6A/cm2,腐蚀阻抗为20106.5 Ω/cm2,耐腐蚀性较Ni-P合金有所提高。(3)以桦木为基材,硅烷前处理后采用钯活化工艺,得出的较优镀液组成和工艺条件如下：硫酸镍27.5 g/L,钼酸铵0.6 g/L,次亚磷酸钠24 g/L,醋酸钠12.5 g/L,柠檬酸三钠27.5 g/L,pH值9.5,施镀时间50 min,施镀温度85℃；磁屏蔽效能测试表明,镀后单板的电磁屏蔽效能达到45 dB以上,与桦木素材相比有明显提高；SEM测试得到,镀后的桦木单板镀层覆盖均匀,具有金属光泽,同时也保留了木材本身的纹理特征。XPS和EDS测试表明,镀层含有Ni、Mo和P三种元素,Ni为主要成分,含量高达92.05%,Mo和P的含量较少,分别为6.86%和1.09%。XRD测试表明,Ni-Mo-P三元合金镀层属于晶态结构；结合强度测试中镀层与木材没有完全分离,得出Ni-Fe-P合金镀层与木材表面结合强度较高；镀后单板的初始接触角为115°,15s后接触角仅下降了1°,单板表面由镀前的亲水性转变为镀后的疏水性；Ni-Mo-P三元合金镀层的腐蚀电位为-0.3010 V,腐蚀电流为密度为4.522×10-6A/cm2,腐蚀阻抗为8244.0 Ω/cm2,耐腐蚀性显著提高。通过对木材表面化学镀镍基三元合金的研究,获得了具有耐腐蚀性的木质基电磁屏蔽材料,为木材表面金属化修饰提供了新思路,为木材科学与技术的发展起到积极的推动作用。更多还原

【Abstract】 Wood is a natural organic polymer material with light weight and renewable properties. However, dry wood is electrical insulator, which limits its application in many fields. Endowing a metal layer on the wood surface is an important way to expand the application field of wood. Electroless plating is the most effective approach to prepare wood-based composite via metal or alloy coating deposition on wood surface. In recent years, the research of electroless plating on wood surface has been rapidly improved. It has been focused on electroless deposition of copper or binary alloy on wood surface to endow wood with new properties. But copper or binary alloy deposits have the disadvantage of poor corrosion resistance, which limits the application of materials for a long time. Therefore, electroless deposition of Ni-based ternary alloy on wood surface is an important way to improve corrosion resistance. In this work, triplochiton sclexcylon and birch veneer were used as substrates and the metal deposition rate and surface resistivity were as the reference value to obtain the optimal plating solution of Ni-based ternary alloy. The coating properties were characterized and tested. The results are as follows:(1) In the process of electroless Ni-Fe-P plating on APTES-treated triplochiton sclexcylon veneer, sodium hypophosphite as reducing agent, the optimal pretreatment conditions are as follows:1.5% APTES stored for five hours, wood samples were dipped into PdCl2 (2 g/L) solution for 10min, next, the resulting samples were immersed in NaH2PO2 solution (2 g/L) for 10 min. The suitable plating bath composition and plating conditions are as follows:45 g/L of nickel sulfate,17.5 g/L of ammonium ferrous sulfate,27.5 g/L of sodium hypophosphite,70 g/L of potassium sodium tartrate,40 g/L of ammonium sulfate, pH value 9.2,90 ℃ for 40 min. The shielding effectiveness value of plated veneer exceeded 45 dB in frequencies from 9 kHz to 1.5 GHz. VSM results showed that the veneer-based composite exhibits higher magnetism. SEM results showed that the coatings were uniform, continuous and compact, and the special structure of wood was still seen clearly. XPS results investigated that the coating was consisted of Ni0, Fe0 and P0, Ni was the main component with 92.51 wt.%, but the contents of Fe and P were 5.57 wt.% and 1.92 wt.%, respectively. The XRD analysis indicated that the coating was crystalline. Adhesion test results showed that the adhesion strength between Ni-Fe-P alloy coating and wood surface was high. The contact angle of single plate was 104°, and decreased 6° after 15 s. The corrosion potential of Ni-Fe-P ternary alloy coating was -0.301 V, the corrosion current density was 7.58×10-6 A/cm2, and the polarization resistance was 3652.9 Ω/cm2. Corrosion resistance of Ni-Fe-P coating was obviously higher than that of Ni-P coating.In the process of electroless Ni-Fe-P plating by using Pd-free activation method, the pretreatment for triplochiton sclexcylon veneer is that the veneers were immersed in 4g/L of KBH4 (3 g/L NaOH) solution for 8min. The plating solution composition and conditions for triplochiton sclexcylon veneer are as follows:45 g/L of nickel sulfate,17.5 g/L of ammonium ferrous sulfate,25 g/L of sodium hypophosphite,70 g/L of potassium sodium tartrate,25 g/L of ammonium sulfate, pH value 9.4,90 ℃ for 60 min. The shielding effectiveness value of plated veneer exceeded 50 dB in frequencies from 9 kHz to 1.5 GHz. VSM results showed that the veneer-based composite exhibits higher magnetism. SEM results showed that the coatings were uniform, continuous and compact, and the special structure of wood was still seen clearly. XPS results verified that the coating was consisted of Ni0, Fe0 and P0, Ni was the main component with 93.60 wt.%, but the contents of Fe and P were 4.71 wt.% and 1.69 wt.%, respectively. The XRD analysis indicated that the coating was crystalline. Adhesion test results showed that the adhesion strength between Ni-Fe-P alloy coating and wood surface was high. The contact angle of single plate was 110°, and decreased 2° after 15 s. The corrosion potential of Ni-Fe-P ternary alloy coating was -0.3610 V, the corrosion current density was 7.89×10-6 A/cm2, and the polarization resistance was 4160.9 Ω/cm2. The coating obtained by this method exhibited excellent corrosion resistance.(2) Ni-W-P coatings were plated by using Pd-free activation and birch as substrate. The suitable bath composition and plating conditions are as follows:22.5 g/L of nickel sulfate,17.5 g/L of sodium tungstate,27.5 g/L of sodium hypophosphite,25 g/L of sodium citrate,5 g/L of lactic acid,30 g/L of ammonium chloride, pH value 8.8,88 ℃ for 40 min. XPS results show that the coating was consisted of Ni0, W0 and P0, Ni was the main component with 89.80 wt.%, but the contents of W and P 4.48 wt.% and 5.72 wt.%, respectively. The XRD analysis indicated that the coating was microcrystalline crystalline. SEM results showed that the coatings were uniform, continuous and compact, and the special structure of wood was still seen clearly. The shielding effectiveness value of plated veneer exceeded 40 dB in frequencies from 9 kHz to 1.5 GHz. Adhesion test results showed that the adhesion strength between Ni-W-P alloy coating and wood surface was high. The contact angle of single plate was 119°, and decreased 2° after 15 s. The corrosion potential of Ni-W-P ternary alloy coating was -0.3400 V, the corrosion current density was 2.163 ×10-6 A/cm2, and the polarization resistance was 20106 Ω/cm2. Compared with Ni-P coating, Ni-W-P coating showed better corrosion resistance.(3) Ni-Mo-P coatings were obtained by using APTES-Pd activation and birch as substrate. The suitable bath composition and plating conditions are as follows:27.5 g/L of nickel sulfate,0.6 g/L of ammonium molybdate,24 g/L of sodium hypophosphite,27.5 g/L of sodium citrate,12.5 g/L of sodium acetate, pH value 9.5,85 ℃ for 50 min. The shielding effectiveness value of plated veneer exceeded 45 dB in frequencies from 9 kHz to 1.5 GHz. SEM results showed that the coatings were uniform, continuous and compact, and the special structure of wood could be still seen clearly. XPS results show that the coating was consisted of Ni0, Mo0 and P0, Ni was the main component with 92.05 wt.%, but the contents of Mo and P 6.86 wt.% and 1.09 wt.%, respectively. The XRD analysis indicated that the coating was crystalline. Adhesion test results showed that the adhesion strength between Ni-Mo-P alloy coating and wood surface was high. The contact angle of single plate was 115°, and decreased 1° after 15 s. The corrosion potential of Ni-Mo-P ternary alloy coating was-0.3100 V, the corrosion current density was 4.522 × 10-6 A/cm2, and the polarization resistance was 8244.0 Ω/cm2, the corrosion resistance improved significantly.The wood-based composites with corrosion resistant and electromagnetic shielding effectiveness were obtained by using electroless Ni-based ternary alloy plating on wood surface. This method provides a new way for wood surface metallization, and plays a positive role for the development of wood science and technology.更多还原