The tribological characteristics of electroless NiP coatings (original) (raw)
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Tribology of Electroless Ni-P Coating Under Lubricated Condition
International Journal of Surface Engineering and Interdisciplinary Materials Science, 2017
Friction and wear behavior of electroless Ni-P coating under lubricated condition is studied on a block – on – roller type tribo – tester by varying applied normal load, sliding speed of the roller and sliding time. Electroless Ni-P coating is deposited on AISI 1040 steel substrates. Surface morphology, phase transformation, composition and analysis of wear mechanism are done using scanning electron microscope, X-ray diffraction techniques and energy dispersive X-ray analysis respectively. Based on Taguchi experimental data, a multiple regression model is fitted to relate the coefficient of friction and wear depth with the tribo – testing parameters. Three dimensional surface and contour plots are generated to analyze the trends in variation of the response variables with the interaction of the process parameters (load, speed and time). Significant improvement in wear depth and COF of electroless Ni-P coating is observed under lubrication. Optimization of wear depth and coefficient ...
The International Journal of Advanced Manufacturing Technology, 2012
Electroless nickel (EN) coatings are used in a wide range of applications concerning their excellent mechanical and tribological properties. The incorporation of solid lubricants, such as polytetrafluoroethylene (PTFE), could even improve the properties of the EN coatings. Above all, we can achieve a film with self-lubricating and excellent anti-sticking characteristics. These uses of electroless nickel coatings are widespread in dry contacts. However, it is well known that in the mechanical components there are a large number of applications that require especially low friction, usually not compatible with the use of unlubricated contacts. Moreover, nowadays, there is a general concern with the environmental impact in the use of lubricants. The tendency is to use fluids with small environmental impact, reducing the contamination made by lubricants of mineral origin. Hence, the aim of the present work was to investigate and improve the understanding of the behaviour of EN and EN + PTFE coatings under lubricated contacts using biolubricants. Tests of coated cylinders were done in lubricated contact against hard AISI 52100 steel on a crossed cylinder sliding tester. The tests were carried out varying widely both the sliding speed and the normal applied load. To allow the comparison of different lubricants, Stribeck curves were used. The influence of the different lubricants under study on the wear amount was investigated by measuring the wear scar on the end of each test. Scanning electron microscopy was used to identify the wear mechanisms.
Friction and wear of electroless NiP and NiP+PTFE coatings
Wear, 2005
In the past 30 years, electroless nickel (EN) plating has grown to such proportions that these coatings are now found underground, in outer space, and in a myriad of areas in between. The first criteria to use electroless nickel generally falls within the following categories: corrosion and wear resistance, hardness, lubricity, uniformity of deposit regardless of geometries, solderability and bondability and nonmagnetic properties. An important property is the amorphous structure in the as-plated condition and the ability to heat treat the deposit by precipitation hardening. Moreover, in order to improve the mechanical and tribological properties of the EN coatings (NiP) further, a EN-polytetrafluoroethylene (NiP + PTFE) composite coating can be obtained that provides even greater lubricity than that which naturally occurs in the nickel-phosphorous alloy deposit. The aim of the present work was an investigation of the friction and wear characteristics of NiP and NiP + PTFE coatings in sliding contacts against hard chromium steel. The role of heat treatment of the coating is discussed.
Tribological Properties of Electroless Co-Deposited Ni-P/Talc Composite Coatings
This study takes place in the scope of the property assessments of Nickel-Phosphorus coatings filled with Talc particles. The NiP matrix is proposed as an alternative to chromizing and the Talc was chosen for its lubricating properties and overall its high temperature behaviour. Tribological experiments with steel pin on coating disk configuration were carried out at ambient temperature and at 600°C. Heat pre-treatments at 420°C and 600°C were conducted to change properties of the studied coatings. Results reveal very good wear behaviour of the pre-treated NiP-talc coatings in dry friction at ambient temperature. At high temperature, wear mechanisms are significantly intensified and implies samples as well as sliders.
Study of Tribological Properties of Ni-P Coatings Under Lubrication
2013
This work presents an experimental study of tribological performance of electroless Ni-P coating under lubricated condition using grey relational analysis. Mild steel specimens are used as the substrate material for the deposition of Ni-P coating. Tribological tests are carried out based on L27 orthogonal array(OA) of Taguchi analysis varying three test parameters viz. normal load, sliding speed and sliding time in a multi-tribotester using block-on-roller configuration in lubricated condition. The experimental results for friction coefficient and wear are analysed using grey relational analysis coupled with Taguchi analysis. An optimal test parameter combination is found out for minimum wear and friction coefficient. It is seen that the normal load is the most significant factor followed by sliding speed and sliding time at 99% confidence level. Finally, a confirmation test is carried out to validate the analysis. The surface morphology and composition analysis of the coatings are ...
Study of wear and friction of chemically deposited Ni-P-W coating under dry and lubricated condition
Surfaces and Interfaces, 2017
In the present work, ternary NiP -W coating is deposited on mild steel substrates from an alkaline hypophosphite based electroless bath. The coatings are characterized in terms of their composition, phase structure and surface morphology using energy dispersive X-ray analysis, X-ray diffraction analysis and scanning electron microscope. It is seen that the coatings exhibit a mixture of X-ray amorphous and nanocrystalline nature in their as-deposited condition due to the co-deposition of tungsten and turns crystalline on heat treatment at 400°C for 1h. A typical nodular surface morphology is observed in scanning electron micrographs. Microhardness and surface roughness of the coatings are also reported. Tribological characterization of the coatings are carried out on a pin-on-disc configuration tribo-tester by varying the test parameters namely the applied normal load, sliding speed and sliding duration with coefficient of friction and wear depth being the responses. The tests are carried out under lubrication as well as in dry condition to strike a comparison between the two environments. Wear depth is seen to increase with an increase in the applied normal load, sliding speed as well as sliding duration under lubricated condition. The variation of COF under lubricated condition is seen to be quite complex due to the synergistic effects of the tribo-testing parameters, lubrication, coating surface morphology and microstructure. A noteworthy improvement in the tribological behavior of NiP -W coating is achieved under lubricated sliding condition.
Influence of the heat treatment on the abrasive wear resistance of electroless Ni-P
Surface and Coatings Technology, 1997
Electroless Ni-P coatings on plain carbon steel werr prepared by using an acid bath based on NiClz as source of nickel cations. Hear-_----___ __-_ treatments were performed at 260' and 300°C for 25 h and 1 h, respectively. The abrasive resistances of the coatings which suffered different heat treatments were determined by using the modified ball cratering method, recently proposed by Staia et al. The abrasive media employed was a mixture of 100 ml ethylene glycol and I g of 3 pm diamond paste. A RB3S.UGlOOP3 ball-bearing was used as tribological pair. The individual wear constants for the substrate and coatings were determined from the recorded plots of the crater depth vs. sliding distances with the aid of theory of the imposed shape wear scar reported in the literature by Kassman et al. Electron microscopy was used to study the morphology of the worn surfaces. As a result, it was found that the heat treatment decreases the abrasive wear resistance of the coatings. A comparison between the methods proposed by Rutherford and Hutchings and ours for assessing the wear constants is carried out, particularly in relation to the relevance of including in the computation the value of the friction force. 0 1997 Elsevier Science S.A.
Widyariset, 2018
Coating process of martensitic stainless steel 420 (SS 420) as the base material component of the steam turbine blade component uses an Electroless NiP coating process. This process is one of the solution coatings that applied to stainless steel as a substrate to improve corrosion resistance. The goal of this research is to get an idea and information about the effect of surface roughness and stirring speed on the characteristics of Electroless NiP layer. Experimental parameters in this research were variations of 0.044 μm, 0.056 μm, 0.101 μm, and 0.164 μm surface roughness and variations of 4.9 rpm, 11.3 rpm, and 21.3 rpm stirring speed. Results showed that the surface roughness and low stiring speed causes the grain distribution becomes more uniform, whichis shown by Scanning Electron Microscopy (SEM) examination. Adhesion layer also increases along with increasing levels of surface roughness. The highest value of adhesion was 1.9 MPa at 0.164 μm and the lowest value of adhesion was 0.8 MPa at 0,044 μm.
Study of tribological properties of electroless Ni – P – Al 2 O 3 composite coatings
2013
Electroless plating technique has been applied to prepare Ni–P composite coatings containing Al2O3 particles on mild steel substrate. Alumina particles with various contents from 5 to 15 g/L in bath are codeposited within Ni–P deposits. The effect of coating parameters such as nickel sulfate and sodium hypophosphite concentration on surface roughness, hardness, and tribological properties are investigated. Coatings are characterized by SEM for surface morphology and EDX for analyzing elemental composition. Coating with Al2O3 concentration of 15 g/L, nickel sulphate of 40 g/L, sodium hypophosphite concentration of 20 g/L, and with heat treatment at 400°C shows maximum coefficient of friction of 0.425, minimum wear loss of 0.36 mg, and micro-hardness of 1506 HV0.05.
Investigation of Tribological Properties under Dry Condition of Chemically Deposited Ni-P-W Coating
Materials Today: Proceedings, 2017
In the present work, the tribological behavior (friction and wear) of NiP -W coating with varying normal load, sliding speed and sliding duration on a pin-on-disc tribo-tester under dry condition is investigated. It is seen that wear depth increases with load, speed and time. A low coefficient of friction is noticed due to the self lubricating nature of the coatings. The microhardness and surface roughness are evaluated prior to the tribological tests. Also, coating characterization is done using scanning electron microscope, energy dispersive X-ray analysis and X-ray diffraction technique. The wear mechanism is predominantly abrasive.