Wyniki wyszukiwania - BazTech

1

The infuence of turning and burnishing on corrosion resistance of laser cladded Fe-Cr-Ni layer from viewpoints of thermodynamics and kinetics

Zhang Peirong, Ji Guosheng, Lv Tao, Hu Shunrui, Wang Bing, Liu Zhanqiang

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 1

art. no. e3, 2023

EN

Laser cladding is commonly used to improve the wear and corrosion resistance of the substrate material. However, mechanical machining is necessary, because the surface irregularities and poor surface roughness after laser cladding. It is urgent to investigate the effect of machining on the corrosion resistance of the laser cladded layers, so as to avoid the reduction of corrosion resistance due to the use of inappropriate cutting parameters. In the present study, the influence of turning-induced surface roughness on the corrosion resistance from the viewpoint of corrosion potential was analyzed first. The corrosion potential is the result of the effect of roughness height parameters and functional parameters. Second, the effect of the machining and subsequent burnishing on the corrosion resistance was analyzed by comparing the corrosion behaviors of the turned and burnished surfaces. The polarization resistance is critically increased by subsequent burnishing. Third, the sensitivity of the machined surface on corrosion resistance was analyzed by EIS method. The strengthening mechanism of machining and subsequent burnishing on the corrosion resistance was determined. On the basis of this research, it is expected to be used to guide the selection of appropriate feed parameter in prior turning to improve the strengthening effect of subsequent burnishing, and then, to improve the surface integrity and corrosion resistance of the laser cladded layer.

2

Protection properties of conversion coatings based on nitrates for resorbable Mg alloy

Cesarz-Andraczke Katarzyna

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2021

|

Vol. 69, nr 1

art. no. e136045

EN

In this work, conversion coatings based on nitrates Ca(NO 3) 2 and Zn(NO 3) 2 were produced on the surface of MgZn49Ca4 to protect against corrosion. The main aim of this study was to prepare dense and uniform coatings using a conversion method (based on nitrates Ca(NO 3) 2 and Zn(NO 3) 2) for resorbable Mg alloys. The scientific goal of the work was to determine the pathway and main degradation mechanisms of samples with nitrate-based coatings as compared with an uncoated substrate. Determining the effect of the coatings produced on the Mg alloy was required to assess the protective properties of Mg alloy-coating systems. For this purpose, the morphology and chemical composition of coated samples, post corrosion tests and structural tests of the substrate were performed (optical microscopy, SEM/EDS). Immersion and electrochemical tests of samples were also carried out in Ringer’s solution at 37°C. The results of immersion and electrochemical tests indicated lower corrosion resistance of the substrate as compared with coated samples. The hydrogen evolution rate of the substrate increased with the immersion time. For coated samples, the hydrogen evolution rate was more stable. The ZnN coating (based on Zn(NO 3) 2) provides better corrosion protection because the corrosion product layer was uniform, while the sample with a CaN coating (based on Ca(NO 3) 2) displayed clusters of corrosion products. It was found that pitting corrosion on the substrate led to the complete disintegration and non-uniform corrosion of the coated samples, especially the CaN sample, due to the unevenly-distributed products on its surface.

3

Investigations of corrosion behaviour of SnSb12Cu6Pb alloy in 0.1M H2SO4 and 0.5M NaCl solution

Hrabia-Wiśnios J., Leszczyńska-Madej B., Kowalik R.

Journal of Achievements in Materials and Manufacturing Engineering

|

2020

|

Vol. 101, nr 1

5--14

EN

Purpose: The results presented the microstructure and corrosive behavior of SnSb12Cu6Pb alloy (B82) in H2SO4 aqueous solution and NaCl aqueous solution. Design/methodology/approach: The electrochemical corrosion has been investigated in two different aqueous solutions: 0.1M sulfuric acid (H2SO4) and 0.5M sodium chloride (NaCl) solution measuring of potential changes relative to immersion time and conducting mass loss test. Microscopic investigations before and after corrosion tests were made using scanning electron microscopy. Findings: The obtained results indicate very good corrosion resistance of the alloy tested in NaCl solution. Corrosion progresses faster in a sulfuric acid aqueous solution compared to sodium chloride aqueous solution. Also, it was found that the dominant mechanism of corrosion degradation in both solutions is selective corrosion which is a particularly undesirable type of corrosion because it involves the loss of one alloying component and the formation of porous structure on the alloy surface. Research limitations/implications: The aqueous solutions used in this study are not a natural working environment of the bearing. However, a comparison of acidic and neutral solutions allows explaining the corrosion behavior of tin babbitts due to contaminants of oil lubricants. Further research should be conducted in more aggressive environments characteristic of industrial conditions. Practical implications: One of the important properties of bearing alloys are corrosion resistance. Corrosion properties are extremely important for the transport and storage of metallic components before they are used. Also, the working environment can have a destructive effect on the properties of the materials used. Industry environment, aging stagnant oil, and some acids may lead to selective corrosion of the tin, copper, lead, or antimony components and leaving a rough and weakened the babbitt surface. Electrochemical corrosion can contribute to the acceleration of bearing wear and consequent to bearing damage. Originality/value: Studies of the corrosion of tin-babbitt bearings are not extensive in the literature due to rare tin corrosion. This study could be an important complement to knowledge about the corrosion behavior of tin-based bearing alloys.

4

The effect of shot peening on the corrosion behaviour of Ti-6Al-4V alloy made by DMLS

Żebrowski R., Walczak M.

Advances in Materials Science

|

2018

|

Vol. 18, nr 3(57)

43--54

EN

Additive Manufacturing processes are being used increasingly in the scope of medicine and dentistry. As indicated by literature data, the durability and quality of medical implants is decisively influenced by surface modification. Insufficient quality of surface finishing leads, among others, to reduced service life of applied implants and to increased number of necessary revision surgeries. Furthermore, various types of finishing processes e.g. cleaning, shot peening or abrasive techniques are suggested by the manufacturers of products made by means of DMLS processes. Due to this fact, the analysis of proper formation of the surface layer of titanium products made by means of the method consisting in the direct laser sintering of metal powders (DMLS) was the subject matter of our research. Therefore, Ti-6Al-4V titanium alloy has been used for tests. The samples have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders. The surfaces of prepared samples have been subjected to shot peening process at three different values of working pressure (0.2, 0.3 and 0.4 MPa) by means of three different working media i.e. CrNi steel shot, crushed nut shells and ceramic balls. The characteristics of the materials used for shot peening process have been determined by means of Zeiss Ultra Plus scanning electron microscope. The samples have been subjected to profilometric measurements on Bruker Contour GT optical profilometer and the corrosion behaviour of Ti-6Al-4V titanium alloy in Ringer solution has been determined in electrode impedance spectroscopy (EIS) measurements by means of Atlas 0531 set dedicated for corrosion testing. The overall results of all tests indicate to favourable influence of the shot peening process on the corrosion behaviour of titanium alloy.

5

Corrosion behaviour of aluminium matrix composites reinforced with sintered halloysite nanotubes

Dobrzański L. A., Reimann Ł., Kujawa M., Tomiczek B.

Journal of Achievements in Materials and Manufacturing Engineering

|

2015

|

Vol. 73, nr 2

92--99

EN

Purpose: The aim of this study was to determine the effect of mass fraction and sintering temperature of the halloysite nanotubes on the corrosion behavior of the infiltrated AlSi12 matrix composites, concerning the matrix alloy. Design/methodology/approach: The corrosion resistance research was done with a potentiodynamic method. Electrochemical corrosion research was made in water centre of 3% NaCl at room temperature. Electrochemical studies of corrosion resistance were performed by determine the open circuit potential and saving the anodic polarization curves by applying to potential changes in the direction of anode and cathode at 1 mV/s. Based on the registered anodic polarization curves were determined: corrosion potential, passive layer breakdown potential, corrosion current density, polarization resistance. The value of corrosion current was determined using the Tafel extrapolation. Findings: Mass fraction of the halloysite nanotubes does not affect the corrosion resistance of the composites as opposed to their sintering temperature. The increase in temperature of a 200°C resulted in a significant reduction in corrosion resistance, but it is still higher than the corrosion of the matrix material. Practical implications: The aluminium alloy matrix composites reinforced with sintered preforms made by sintering halloysite nanotubes are modern materials that could find application in the automotive industry. The mechanical properties are greater than the alloy matrix while retaining a low density. It was necessary to examine the corrosion resistance as one of the important properties of the composites which are exposed to corrosive environments. Originality/value: Beyond the articles of the authors, analysis of mechanical properties and corrosion resistance of the infiltrated AlSi12 matrix composites reinforced by preform made by sintered halloysite were not found in the available literature.

6

Studies of corrosion behaviour in acid environment of binary Mg-Li alloys for plastic forming

Białobrzeski A., Saja K., Żmudzińska M.

Archives of Foundry Engineering

|

2011

|

Vol. 11, iss. 3 spec.

25--28

EN

The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an acid medium (5% HCl solution) for the time of 0-144 hours. In short it can be stated that corrosion of the examined Mg-Li alloys in 5% HCl solution proceeded in a similar mode in all the studied alloys, regardless of the lithium content.

7

Azotowanie plazmowe i jego wpływ na odporność korozyjną stali nierdzewnych

Flis J.

Ochrona przed Korozją

|

2005

|

nr 4

86-89

PL

Azotowanie jest szeroko stosowane w celu zwiększenia wytrzymałości zmęczeniowej, twardości i odporności na zużycie. Azotowanie stali chromowych w temperaturach ok. 550-580oC powoduje wydzielanie azotków chromu, co prowadzi do znacznego polepszenia własności tribologicznych, ale także do pogorszenia odporności korozyjnej; azotowanie w niższych temperaturach ok. 380-450oC może polepszyć odporność korozyjną dzięki powstawaniu przesyconego stałego roztworu azotu bez wydzieleń obcych faz. Niniejszy artykuł opisuje korozyjne zachowanie plazmowo azotowanych stali nierdzewnych i metody zwiększenia ich odporności na korozję. Znaczną poprawę odporności po wysokotemperaturowym azotowaniu (550-580oC) uzyskano po pasywacji w roztworze NaOH/KNO3 lub w soli stopionej NaNO3/KNO3, a zwłaszcza po fosforanowaniu. Azotowanie nisko-temperaturowe powodowało silny wzrost odporności na korozję wżerową w roztworach chlorkowych. Analiza AES/XPS powierzchniowych produktów korozji wykazała powstawanie na stalach po nisko-temperaturowym azotowaniu większych ilości związków Cr(III), Mo(IV) i Mo(VI) mających działanie inhibicyjne; nagromadzanie tych związków może być powodem dużej odporności na korozje wżerową.

EN

Nitriding is widely used for increasing the fatigue strength, hardness and wear resistance of steels. Nitriding of chromium-bearing steels at temperatures of about 550-580oC results in the formation of chromium nitride precipitates which lead to a strong improvement of tribological properties, but also to a deterioration of corrosion resistance; nitriding at lower temperatures of about 380-450oC can enhance the corrosion resistance owing to the formation of a supersaturated solid solution of nitrogen without precipitates. This article describes the corrosion behaviour of plasma nitrided stainless steels and methods for increasing their corrosion resistance. A significant improvement of corrosion resistance after high-temperature nitriding (550-600oC) was achieved by passivation in a NaOH/KNO3 solution or in a molten NaNO3/KNO3 mixture, and particularly by phosphating. Low-temperature nitriding resulted in a strong increase of resistance to pitting corrosion in chloride solutions. An AES/XPS analysis of surface corrosion products showed that on low-temperature nitrided steels, the amount of inhibitive species Cr(III), Mo(IV) and Mo(VI) was larger; an increased amount of these species can be responsible for a high resistance to pitting corrosion.