Mechanical assisted electroless barrel-plating Ni-P coatings on magnesium alloy

A mechanically assisted electroless barrel-plating Ni-P was carried out in a rolling drum containing Mg alloy specimens and ceramic balls, which was submerged in a bath containing electroless plating solution deposited by this novel technique have a It is demonstrated that the Ni-P coatings crystallized Ni-P solid solution structure, showing fine-grains, higher hardness, and higher corrosion resistance compared with the conventional electroless plated amorphous Ni-P coatings. After heat treatment at 400 ℃ for 1 h, the structure of such Ni-P coatings were transformed to a structure with Ni-Ni3P double phases, and cracks in these coatings could not be observed, whereas cracks appeared seriously in the conventional electroless plated Ni-P coating after same heat treatment. Therefore, both hardness and corrosion resistance of these Ni-P coatings can be improved further by heat treatment. All of these beneficial effects can be attributed to the role of mechanical attrition during the mechanically assisted electroless barrel-plating process.

High-temperature tribological properties of Ni-P alloy coatings deposited by electro-brush plating

High-temperature tribological properties of Ni-P alloy coatings processed by electro-brush plating on 20CrMo steel have been investigated. A baU-on-disc configuration was employed and 4 mm diameter Si3N4 balls were used as static counterpart. All the wear tests were carried out at 450℃ for 180 rain without lubricants. The electro-brush plating Ni-P coating is amorphous in as-deposited condition, and it becomes polycrystalline with the formation of Ni and Ni3P after heat treatment at 450℃for 1 h. The friction coefficient of the Ni-P coating is just 50% of that of the 20CrMo steel at the friction temperature of 450℃. A mild adhesive wear mechanism was found for the electro-brush plating Ni-P coating tested at 450℃, whereas for the 20CrMo steel at the same temperature a mixed adhesive and abrasive wear mechanism was observed.

Erosion and Toughening Mechanisms of Electroless Ni-P-Nano-NiTi Composite Coatings on API X100 Steel under Single Particle Impact

The addition of superelastic NiTi to electroless Ni-P coating has been found to toughen the otherwise brittle coatings in static loading conditions, though its effect on erosion behaviour has not yet been explored. In the present study, spherical WC-Co erodent particles were used in single particle impact testing of Ni-P-nano-NiTi composite coatings on API X100 steel substrates at two average velocities—35 m/s and 52 m/s. Erosion tests were performed at impact angles of 30°, 45°, 60°, and 90°. The effect of NiTi concentration in the coating was also examined. Through examination of the impact craters and material response at various impact conditions, it was found that the presence of superelastic NiTi in the brittle Ni-P matrix hindered the propagation of cracks and provided a barrier to crack growth. The following toughening mechanisms were identified: crack bridging and deflection, micro-cracking, and transformation toughening.

Quality of Electroless Ni-P (Nickel-Phosphorus) Coatings Applied in Oil Production Equipment with Salinity

The corrosion resistance of nickel-phosphorus (Ni-P) coatings and their mechanical properties in seawater have led inestigations into the development of new technologies and the replacement of some special alloys in equipment used in oil production, such as valves, tubing, sucker rod joints, pumps, riser, manifolds and subsea Christmas trees. These studies began with Brenner and Riddel who developed, in the 1940s, formulations for Ni-P deposition on carbon steel without using an electric current. Joint deposition of nickel and phosphorus on a metallic surface (carbon steel) without applying an external current is accomplished using cathodic reduction with hydrogen (H) from a reducing agent (sodium hypophosphite) and nickel salts. To assure good performance of a Ni-P coating, the deposit quality must be inspected and evaluated during the chemical deposition process or in the end product. The recommended test parameters are: thickness, layer uniformity, hardness, adhesion, porosity, corrosion resistance and chemical composition of the nickel-phosphorus coating. The purpose of this paper was to investigate the Ni-P coating process, to evaluate the b?haviour of Ni-P in a saline environment using aqueous brine (3.5% - 30% sodium chloride by mass) and to present possible defects that could compromise the coating.

Ni-P/Ni-W-P双层化学镀的研究

用双层化学镀工艺取代传统的单层化学镀工艺,得到的Ni-P/Ni-W-P镀层比Ni-W-P镀层更均匀﹑细致;同时有着更好的硬度﹑耐磨性和耐蚀性能。

铝合金化学镀Ni-P、Ni-W-P组织及相转变行为

采用差示扫描热分析仪(DSC)、X射线衍射(XRD)等研究了6061铝合金基体化学镀Ni-P、Ni-W-P合金的组织结构及相转变行为。结果表明,镀态Ni-P、Ni-W-P镀层的结构都是微晶结构；200℃热处理1h后,Ni-P、Ni-W-P镀层仍为微晶,但微晶有所长大；300、400、525和600℃热处理1h后,Ni-P、Ni-W-P镀层析出Ni_3P和Ni晶体,没有其它亚稳相析出；400℃时Ni-P、Ni-W-P镀层硬度达到峰值,其值分别为840HV100和940HV100。

激光处理化学沉积Ni-P/Ni-W-P双镀层的显微组织及性能特征(英文)

采用SEM/EDX及XRD定量分析技术研究了化学沉积Ni-P/Ni-W-P双镀层激光晶化前、后的组织特征,并通过表面和截面的硬度测量以及干摩擦磨损实验评估了双镀层的硬度及耐磨性。结果表明,在两种不同的镀液中连续沉积可以制备出Ni-P/Ni-W-P双合金镀层。激光晶化处理后,化学沉积Ni-P/Ni-W-P双镀层表现出外层NiWP比内层NiP更高的晶化程度及更大的晶粒尺寸,但外层具有更高的硬度。激光处理的双镀层在给定的加工条件下,其耐磨性优于镀态镀层的。激光处理可直接在空气中进行而不需要氩气保护,这为工业化应用提供了可能性。

W含量对Ni-P/Ni-W-P双层镀层性能的影响

在化学镀条件下,研究了W含量对Ni-P/Ni-W-P双层镀层的表面形貌、耐蚀性能和硬度的影响。结果表明,在中钨条件下的镀层具有更好的耐蚀性能和更高的硬度。

化学镀Ni-W-P或Ni-P合金与油溶性有机钼的协同作用

在45调质钢基体上化学镀Ni W P或Ni P镀层.。在基础油中加入3%的二烷基二硫代磷酸钼(简称MoDTP)添加剂.,研究了化学镀Ni W P或Ni P镀层与MoDTP的复合摩擦学性能。结果表明,Ni W P或Ni P镀层与油溶性有机钼有良好的协同效应。

7075铝合金化学镀Ni-P/Ni-W-P双层镀层研究

以7075铝合金为基体,采用直接连续化学镀法制备Ni-P/Ni-W-P双层膜,并采用SEM,EPMA,XRD和显微硬度计、电化学工作站等对膜层热处理前后的表(断)面形貌、成分、结构、硬度和耐腐蚀等性能进行了研究。结果表明:获得了致密无孔且与基体及层间相互结合紧密的非晶态Ni-P/Ni-W-P膜;热处理后,镀层硬度提高,而耐蚀性略有降低。

Crystalline texture evolution, control of the tribocorrosion behavior, and significant enhancement of the abrasion properties of a Ni-P nanocomposite coating enhanced by zirconia nanoparticles

This paper describes an investigation of the effect of ZrO2 nanoparticles on the abrasive properties,crystalline texture developments,and tribocorrosion behavior of Ni-P nanostructured coatings.In the investigation,Ni-P and Ni-P-ZrO2 nanostructured coatings are deposited on St52 steel via the electroless method.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),cyclic-static polarization tests in 3.5wt%NaCl solution,the tribocorrosion test(by back-and-forth wear in electrochemical cell),and the microhardness test using the Vickers method were performed to characterize and analyze the deposited coatings.The results of this study showed that the addition of ZrO2 nanoparticles to the Ni-P electroless bath produced the following:a sharp increase in wear and hardness resistance,the change of the wear mechanism from sheet to adhesive mode,the reduction of pitting corrosion resistance,significant reduction in the tribocorrosion protective properties,change in the preferred orientation of the crystalline texture coating from(111)to(200),increase in the sedimentation rate during the deposit process,and a sharp increase in the thickness of the Ni-P nanostructured coatings.

激光退火对化学镀Ni-W-P/Ni-P梯度镀层组织及硬度的影响

通过成分分析、形貌观察、小角XRD衍射定量分析、显微硬度测试、深度敏感压痕技术(DSI)测试等方法,研究了激光退火对化学镀Ni-W-P/Ni-P梯度镀层组织及硬度的影响。结果表明:激光扫描速度由12 mm/s降低到8 mm/s,外层结晶度由70. 3%提高到85. 3%,内层结晶度由50. 3%提高到69. 5%。内层Ni3P的质量分数始终高于相应外层。激光退火镀层硬度显著提高,扫描速度越低,镀层硬度越高,最高硬度出现在扫描速度为8 mm/s的外层,达到898 HV0. 1。激光扫描速度为10 mm/s时,内层硬度(779 HV0. 1)略高于外层硬度(782 HV0. 1)。

High-temperature Compressive Performance of Mg Alloy Foams Coated with Ni-P Layer

Mg/Ni hybrid foams were fabricated by the electroless method.The Ni-P(Nickel-Phosphorous)coatings were deposited on the surface of closed-cell Mg alloy foams.The composition,microstructure and phases of the Ni-P coatings were characterized by scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD),respectively.The compressive tests were performed on the Mg/Ni hybrid foams at 400℃using the Mg alloy foams as a reference.The experimental results show that the yield strength,plateau stress and energy absorption capacity of the closed-cell Mg alloy foams at high temperature were improved by the Ni-P coating.And there are four main modes for the Mg/Ni hybrid foam failure at 400℃,i e,shearing in cell wall,bending in cell edge,shedding and cracking in Ni-P coating.

Synergistic Effect between Nano-ceramic Lubricating Additives and Electroless Deposited Ni-W-P Coating

The major solving ways for the material wear are surface modification and lubrication. Currently, the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating. The surface coating has high hardness and high wear resistance, however, the friction reduction performance of the coating with high hardness is not good, the thickness of the coating is limited, and the coating can not regenerate after wearing. The nano-lubricating additives have good tribological performance and self-repair function, but under heavy load, the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair. To solve the above problems, the Ni-W-P alloy coating and deposition process with excellent anti-wear, and suitable for industrial application were developed, the optimum bath composition and process can be obtained by studying the influence of the bath composition, temperature and PH value to the deposition rate and the plating solution stability. The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied. The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives, and the tribology mechanism, to seek the synergetic effect between the two. The test results show that the wear resistance of Ni-W-P alloy coating （with heat treatment and in oil with nano-ceramic additives） has increased hundreds times than 45 steel as the metal substrate in basic oil, the friction reduction performance is improved. This research breaks through the bottleneck of previous separate research of the above-mentioned two methods, and explores the combination use of the two methods in industrial field.

Wear and Corrosion Resistance of Electroless Plating Ni-P Coating on P110 Steel

In order to improve the surface performance and increase the lifetime of P 110 oil casing tube steel during operation, electroless plating was conducted to form Ni-P coating onto its surface. The surface morphology/element distribution and phase constitution of the Ni-P coating were analyzed using scanning electron microscope （SEM） equipped with energy dispersive spectrometry （EDS） and X-ray diffraction （XRD）. Tribological and electrochemical measurement tests were applied to investigate the wear and corrosion resistance of P110 steel and the Ni-P coating. The results showed that a uniform and compact, high phosphorous Ni-P coating was formed. The obtained Ni-P coating indicated certain friction-reduction effect and lower mass loss during friction-wear tests. The Ni-P coating also exhibited higher corrosion resistance in comparison with bared P 110 steel. The obtained N i-P coating has significantly improved the surface performance of P110 steel.

Investigation on a Non-cyanide Plating Process of Ni-P Coating on Magnesium Alloy AZ91D

In this research we presented a non-cyanide plating process of Ni-P alloy coating on Mg alloy AZ91D. By applying a new process flow of electroless nickel plating in which zinc coating is used as transition of Ni-P coating on Mg alloy AZ91D, the process of copper transition coating plated in the cyanides bath can be replaced. A new bath composed of NiSO4 was established by orthogonal test. The results show that zinc transition coating can increase the adhesion and protect the Mg alloy substrate from the bath corrosion. The optimal plating bath composition is NiSO4·6H2O 20 g/L, NaH2PO2·H2O20g/L and C6H8O7·H2O 2.5 g/L, and optimal bath acidity and optimal plating temperature are pH 4.0 and 95℃, respectively. The present process flow is composed of ultrasonic cleaning→alkaline cleaning→acid pickling→activation→double immersing zinc→electroplating zinc→electroless nickel plating→passivation treatment. The present non-cyanide process of electroless nickel plating is harmless to our surroundings and Ni-P coating on Mg alloy AZ91D produced by present process possesses good adhesion and corrosion resistance.

Study on Corrosion Resistance of Ni-W-P Coating in Hypersaline Brine

Brine resource is rich in China,but its exploitation has been a problem.Hypersaline brine will corrode equipment and materials seriously during the brine exploitation and transportation.The corrosion problem can cause great

The Effect and Mechanism of Nano-Cu Lubricating Additives on the Electroless Deposited Ni-W-P Coating

The coating and deposition process with excellent anti wear and suitable for industrial application were developed, and the optimum bath composition and process were obtained by studying the influence of the bath composition, temperature and pH value on the deposition rate and the plating solution stability. Moreover, the tribological properties of nano-Cu lubricating additives and electroless deposited Ni-W-P coating as well as their synergistic effect are researched using ring-block abrasion testing machine and energy dispersive spectrometer. Research results show that Ni-W-P alloy coating and nano-Cu lubricating additive have excellent synergistic effect, e g, the wear resistance of Ni-W-P alloy coating （with heat treatment and the oil with nano-Cu additives） has increased hundreds times than 45 steel as the metal substrate with the basic oil, and zero wear is achieved, which breaks through the bottleneck of previous separate research of the above-mentioned two aspects.

EFFECTS OF DEPOSITION PROCESS ON PHOSPHORUS CONTENT IN ELECTROLESS Ni－P COATINGS

There are many factors that affect the phosphorus content in the electroless Ni-P coatings The effects of the compositions of plating solution,the PH values of plat ing solution and the deposition temperature on the phosphorus content in Ni-P coatings were investigated in this paper It is found that the phosphorus content in Ni-P coatings increases and the deposition rate decreases with decreasing PH values,nickel sulphate NiSO4 content of plating solution and the deposition temperature.

铝合金化学镀Ni-P合金的研究进展

本文分析了铝合金化学镀的特点,综述了铝合金化学镀Ni-P合金、Ni-W-P等三元合金、Ni-P/Ni-B双层复合镀及Ni-P-微粒化学复合镀的工艺流程及应用。