热处理对压铸镁合金化学镀层组织和性能的影响

采用化学镀方法在AZ91D压铸镁合金表面获得N i-P镀层,研究了不同热处理温度对镀层的组织和性能的影响。结果表明:镍层中P含量为6.22 wt%,镀层组织为非晶+少量纳米晶组织。随热处理温度升高原始镀层中的非晶组织中先形成镍纳米晶,然后纳米晶镍伴随晶化过程进行迅速长大,并在镍基体上析出N i12P5和N i3P相。镀层与基体的结合强度在350℃附近达最大结合强度为3.7 MPa,镀层硬度在400℃附近达最大值为825 HV;盐雾腐蚀实验表明镀层耐腐蚀性能良好,连续盐雾8 h未出现腐蚀斑点。经过不同的热处理,镀层的耐蚀性随着热处理温度的提高而下降。     

Effect of the microstructure on the properties of Ni-P deposits on heat transfer surface

In the present work Ni-P deposits with various microstructures were prepared on the low carbon steel substrate by adjusting the electroless plating processing parameters. The results of anti-fouling experiments show that Ni-P deposits can greatly inhibit the adhesion of crystallization fouling in comparison with uncoated copper, stainless steel and carbon steel surfaces. The further experiments indicated that the amount of nanocrystalline phase in the Ni-P deposit affects the surface free energy, as well as changing the anti-fouling and corrosion-resistant properties of the deposit. When the phase structure of the Ni-P deposit is almost amorphous phase, the Ni-P deposit exhibits the best anti-fouling and corrosion-resistant properties. The amorphous Ni-P deposit exhibits high corrosion resistance which is attributed to its extreme structure homogeneity without preferential corrosion paths like grain boundaries or other structural defects, and the higher corrosion resistance could ensure this deposit is not easy to form “transitional interface” connecting fouling and matrix.     

钨含量对Ni-W-P镀层抗垢性能的影响

采用化学镀的方法,调整化学镀工艺参数中钨酸钠的浓度,在低碳钢（1015）表面获得了钨含量不同的Ni-W-P镀层,分别采用扫面电镜、X射线衍射仪以及MH-6表面硬度计研究了钨含量对Ni-W-P镀层表面形貌、结构以及显微硬度的影响。结果表明,镀液浓度对于获得磷和钨含量起到决定性的作用,而磷和钨的含量决定了Ni-W-P镀层的表面形貌和结构。胞状晶的形成是Ni-W-P镀层的共同特征,镀层中钨含量的增加降低了磷的含量,因此改变了纳米晶相的含量。由于钨固溶于镍中诱使镀层产生固溶强化限制了镀层局部塑性变形,从而增加了镀层的硬度。采用差热分析研究相变行为的结果表明,高钨含量的Ni-W-P镀层表现为较高的晶化温度。进一步的污垢沉积试验表明,与低碳钢表面相比,含有不同钨含量的Ni-W-P镀层表面抑制了污垢的黏附。然而,进一步研究表明,污垢沉积速度和Ni-W-P镀层表面粗糙度之间没有必然的联系,与钨的含量有着直接的联系。     

硫脲对喷射电铸纳米晶铜组织与性能的影响

采用喷射电铸法制备了不同硫脲浓度下的纳米晶铜铸层,用SEM、XRD方法分析了硫脲对纳米晶铜铸层微观结构和晶粒大小的影响,并对纳米晶铜铸层的力学性能进行了测试.结果表明,硫脲能细化晶粒,致密铸层组织,显著提高铸层的抗拉强度和显微硬度;电铸液中硫脲浓度为10 mg/L时,可获得晶粒尺寸为29 nm的致密铜铸层,其显微硬度和抗拉强度分别为3.1 GPa和645 MPa.电铸液中硫脲浓度从5 mg/L增至10 mg/L时,纳米晶铜铸层的择优取向由(220)晶面转变为(111)晶面.     

等温退火对Ni-P、Ni-W-P镀层的晶粒尺寸和显微硬度的影响

研究了不同镀态结构的Ni-P、Ni-W-P镀层经等温退火后，其晶粒尺寸和硬度随退火时间的变化规律，镀层的热稳定性以及成分、结构和晶粒尺寸对镀层硬度的影响规律。结果表明，W元素可以促进Ni-P合金的非晶化，显著提高Ni-P镀层的硬度；Ni-（W）-P体系纳米晶镀层具有较好的热稳定性；等温退火获得的三元Ni-W-P单相纳米晶镀层在耐磨、耐蚀性能方面均优于同类非晶态镀层。     

Effect of PTFE Addition on the Properties of Electroless Ni-Cu-P-PTFE Deposits

采用化学镀的方法,调整化学镀工艺参数,在低碳钢表面获得了PTFE含量不同的Ni-Cu-P-PTFE镀层,研究了PTFE粒子对Ni-Cu-P-PTFE镀层表面形貌、相、显微硬度、结合强度以及摩擦等性能的影响。结果表明,Ni-Cu-P-PTFE镀层的沉积速度随着PTFE浓度的增加而升高。进一步的实验结果表明,由于PTFE颗粒自身的疏松结构和软质特性,PTFE颗粒在镀层中的共沉积会引起Ni-Cu-P-PTFE镀层的显微硬度下降。同时Ni-Cu-P-PTFE镀层的结合强度会随着PTFE浓度的增加而减小。此外,PTFE的添加会使Ni-Cu-P-PTFE镀层的摩擦系数降低,这些结果与PTFE粒子在Ni-Cu-P-PTFE镀层中的含量成反比,而与镀液中PTFE粒子的浓度没有良好的对应关系。     

热处理工艺对Ni-P-PTFE复合镀层组织与性能的影响

采用扫描电镜、X射线衍射、差热分析研究了热处理对Ni-P-PTFE(聚四氟乙烯)化学复合镀镀层组织的影响,并研究了镀层的磨损性能.结果表明,经400℃×1 h处理后,PTFE的挥发主要发生在镀层的表层,内部的PTFE含量变化很小;镀态条件下,镀层为非晶态,经400℃×1 h处理晶化后生成Ni相及Ni3P相.Ni-P-PTFE复合镀层的晶化起始温度和峰值温度都高于Ni-P镀层.Ni-P-PTFE复合镀层的激活能为235 kJ/mol,与Ni-P镀层的激活能差别不大.镀层摩擦系数在PTFE加入量为8 mL/L时最小,同时镀层磨损量最小;热处理后,Ni-P-PTFE复合镀层表现出较好的耐磨性和较小的摩擦系数.     

Process Recycling and Environmental Treatment

A useful coating technology for electroless Ni-1.5wt%P has been developed. The bath can work normally for more than 5 turnovers with a plating rate of 20 μm/h. In the as-deposited condition, Ni-1.5wt%P deposit is a supersaturated solid solution of P dissolved in a nanocrystalline Ni matrix with a grain size of several nanometers. The microstructure transformed into a larger grain size Ni matrix with dispersive Ni₃P precipitates with increasing the heat treatment temperature. Ni-1.5wt%P deposit possesses as-deposited hardness and wear resistance superior to Ni-10.5wt%P deposit. The microhardness and wear resistance can be further improved by proper heat treatment. The optimum wear resistance of Ni-1.5wt%P deposit corresponds to its peak hardness (annealing at 375°C for 1 h), whereas for Ni-10.5wt%P deposit the optimum wear resistance is obtained after annealing at 650°C for 1 h. Ni-1.5wt%Ppossesses a corrosion resistance in NaOH solution superior to conventional medium and high phosphorus deposits, which have much better corrosion resistance in NaCl and HCl solution. The rotating fatigue results indicate that electroless nickel deposits cause a decrease in the fatigue strength of 30CrMo steel, and increase the fatigue strength of LY12 alloy. Ni-1.5wt%P deposit demonstrates higher fatigue resistance than Ni-10.5wt%P deposit.     

锡青铜化学镀 Ni-P 合金工艺及镀层性能

目的在锡青铜基体上化学镀Ni-P合金镀层,提高锡青铜的耐磨性和耐腐蚀性。方法以酸性含锌活化液活化锡青铜试样,在相同的条件下实施化学镀,并对镀态试样进行不同温度(250,400,500℃)下的热处理。对比基体、镀态试样和热处理试样的性能,研究热处理温度对锡青铜化学镀Ni-P合金层微观结构、显微硬度、耐磨性和耐腐蚀性的影响。结果锡青铜表面形成了Ni-P合金镀层,并且镀层无孔隙缺陷,与基体结合良好,沉积速率较快,为10.00μm/h。经热处理后,镀层的微观结构由非晶态向晶态转变,在500℃热处理的镀层显微硬度最大,耐磨性最好。镀态镀层和经250℃热处理的镀层在10%HNO3溶液和10%H2SO4溶液(10%均为体积分数)中的耐腐蚀性明显好于锡青铜基体,镀态镀层在两种介质溶液中的腐蚀速率分别为0.225,0.146 mg/(cm2·d)。结论采用酸性含锌活化液活化锡青铜基体,可以在锡青铜表面制备出化学镀Ni-P合金镀层,且镀覆效果较好。这表明紫铜化学镀Ni-P合金工艺同样适用于锡青铜。     

纳米晶(Ag-Cu28)-25Sn合金粉末的制备及表征

采用机械合金化法制备纳米晶(Ag-Cu28)-25Sn合金粉末.用X射线衍射(XRD)仪、扫描电镜(SEM)、高分辨透射电镜(HRTEM)和差示扫描量热分析仪(DSC)等分析手段,对合金化过程中物相组成、微观结构及熔化特性进行表征.结果表明:(Ag-Cu28)-25Sn纳米晶合金粉末的物相组成为Cu3Sn和Ag4Sn.球磨 40 h,合金化完全,其熔化温度为548.5 ℃;球磨至60 h,合金明显非晶化,其熔化温度为554.0 ℃,熔程变小且在186.3和399.5 ℃处出现明显放热峰.HRTEM表明,纳米晶的尺寸约为5～10 nm,合金中有非晶态物质出现和晶格缺陷产生.200和400 ℃退火后,合金的平均晶粒尺寸分别为21.3和33.9 nm.     

Effects of saccharin and cobalt concentration in electrolytic solution on microhardness of nanocrystalline Ni-Co alloys

Cobalt content, surface morphology and microhardness of nanocrystalline Ni-Co deposits prepared by pulse plating technique at constant electrodeposition conditions with varied concentration of saccharin and cobalt sulfate in the electrolyte were investigated. It is found that appropriate amount of both additions could lead to finer structure and higher hardness of the deposit and further increase of the concentration could result in decline of the hardness, which is regarded as the result of inverse Hall-Petch relation. The maximum hardness of the Ni-Co alloy deposits is not higher than that of their pure Ni counterparts, indicating that the refinement hardening effect (Hall-Petch relation) is dominant in nanocrystalline Ni-Co alloy deposits. By adding Co ions to the electrolyte, the amount of organic refiner saccharin (responsible for introduction of sulfur and carbon impurities) needed to produce nanocrystalline deposits could be remarkably reduced.     

热处理对Ni-P化学镀层阻垢和耐蚀性能的影响

利用XRD研究了化学镀Ni-P合金镀层经不同温度热处理后的结构变化。结果表明,镀态Ni-P呈非晶态;350 ℃时镀层由非晶态向晶态转化;热处理温度为400 ℃时,析出Ni₃P稳定相。镀态及热处理条件下的阻垢和耐蚀性实验结果表明,随着热处理温度的升高,CaCO₃中Ca的原子分数先降低后升高,300 ℃热处理降低了镀层的内应力及氢脆,使镀层的组织更加致密,镀层的阻垢和耐蚀性得到改善。     

Heat treatments for electroless nickel–boron plating on aluminium alloys

Electroless nickel–boron baths reduced with sodium borohydride can be stabilized with various agents such as thallium nitrate or lead tungstate with no fundamental modification of deposition rates and stability. To improve the mechanical properties of electroless nickel–boron deposits, various heat treatments are applied. At low temperatures, no fundamental changes in the deposit structure are observed, only an improvement of adhesion on aluminium substrate. The values of the Knoop microhardness obtained on these heat-treated deposits are near 600 hk₁₀₀. At higher temperatures, structural changes take place and the nickel–boron deposits crystallize. The microhardness rises until 1050 hk₅₀ for heat treatments at 350 °C for 4 h. A diffusion layer between the electroless nickel deposit and the aluminium substrate appears at high heat treatment temperatures. The results of scratch tests show that the Ni–B deposits, with or without heat treatments, have good tribological properties under external solicitations. They are hard, wear and abrasion resistant, and also have good adhesion to the aluminium substrate.     

Effect of Heat Treatment on Microstructure and Mechanical Properties of GH4169 Superalloy

研究了4种热处理制度对GH4169合金显微组织、室温拉伸、650℃拉伸和持久性能的影响。结果表明:980℃固溶加两阶段时效处理,合金的室温和650℃拉伸的屈服强度和抗拉强度最高;960℃固溶加两阶段时效处理,合金的持久寿命最长。固溶处理调整y相的含量,主要强化相y"在720℃时效时析出,辅助强化相y’在620℃时效析出。     

热处理温度对窄深槽类零件环保铬镀层组织与性能的影响

采用环保三价铬电镀工艺对窄深槽类零件进行电镀铬后,再对铬镀层进行不同温度(0～400℃)的热处理,研究热处理温度对窄深槽类零件环保铬镀层组织和性能的影响,并对热处理前后铬镀层的微观形貌、相结构、显微硬度、结合力和耐磨性进行了分析.结果表明:镀态镀层表面存在微裂纹,经热处理后微裂纹间隙扩大,并且随着温度的升高,镀层结构逐...     

Microstructure evolution and hardening mechanisms of Ni-P electrodeposits

Ni-P alloy coatings with different phosphorus contents were prepared by electroplating in a nickel sulfate bath containing phosphorous acid (H₃PO₃). Hardening mechanism, such as dispersion hardening of Ni nano crystals in amorphous matrix of the as-deposited Ni-P coating and coarsening weakening of Ni₃P for the high P coating after 1 h of heat treatment at 400 °C were concluded from the experimental data. Hardening mechanism of Ni-P alloys were further discussed based on the microstructure evolution with increasing deposit P content and during the heat treatment by using high resolution TEM (HR-TEM). A maximum hardness was observed for the as-deposited and heat-treated Ni-P alloys with 4 wt.% and 6 wt.% P, respectively. These composition ranges corresponding to the microstructure with high hardness proposed are believed to be useful for the industrial applications and further study.     

铁基合金化学镀层的显微硬度

通过显微硬度测量和Ｘ射线衍射结构分析，研究了化学镀Ｆｅ－Ｍｏ－Ｂ非晶态合金、Ｆｅ－Ｗ－Ｂ晶态合金镀层的显微硬度随成分、热处理及结构的变化关系。结果表明：两合金系的显微硬度均随类金属Ｂ含量增加而提高，电子浓度的变化规律则相反。且热处理过程中，随退火温度增加，Ｆｅ－Ｗ－Ｂ合金镀层的显微硬度出现峰值，这与晶化析出相的类型及数量有关。     

Effect of Heat Treatment on Structure and Electrochemical Properties of Electro-deposited Ni-P Amorphous Alloy

ELECTROCHEMICAL deposition of Ni-P alloy iswidespread due to the unique physical,chemical andmechanical properties of these materials'11.And moreand more emphasize were laid on the study ofelectrochemical deposition of amorphous Ni-P alloybecause of its unique corrosion resistance.However,the detail reports about the relation of heat treatmenttime and the electrochemical behavior of amorphousNi-P alloy are rare.In this article,the influences of heattreatment time on the structure and t…     

热处理对2.25Cr1MoR钢组织和性能的影响

研究了热处理工艺对2．25Cr1MoR钢组织和力学性能的影响。结果表明，该钢在780℃回火时可获得良好的强韧化效果和较高的抗回火脆性能力，在此基础上得到了该钢板生产制造的热处理工艺参数。实践证明，该工艺合理可行。     

Improved microhardness and wear resistance of the as-deposited electroless Ni-P coating

The coatings with different phosphorus contents were obtained by varying the ratio of lactic acid to acetic acid in the electroless plating bath. With the increase of phosphorus content, the structure of the electroless Ni-P coating transformed from nanocrystalline to a mixture of nanocrystalline and amorphous phases, then to amorphous phase. A record high hardness value of 910 HV_0.1 of as-deposited Ni-P coating was obtained at 7.97 at.% phosphorus content, and high wear resistance was accordingly achieved. The refined nanocrystalline grains with an average size of ~ 4 nm were found to be responsible for the record high hardness and improved wear resistance of the as-deposited Ni-P coating.