rus
Issue #3-4/2021
M.Nasraoui
Chromium galvanic plating modified by a combination of multilayer carbon nanotubes and nanodiamonds
Chromium galvanic plating modified by a combination of multilayer carbon nanotubes and nanodiamonds
DOI: 10.22184/1993-8578.2021.14.3-4.206.211
An experimental study of the microhardness of the obtained chromium plating from a standard electrolyte modified with a combination of multilayer carbon nanotubes (MLCNT) and nanodiamonds was carried out. It was revealed that when the combination of MLCNT of "Taunit" series and nanodiamonds is added to the electrolyte, the microhardness of the chromium coating increases to 1,084 kg/mm2.
An experimental study of the microhardness of the obtained chromium plating from a standard electrolyte modified with a combination of multilayer carbon nanotubes (MLCNT) and nanodiamonds was carried out. It was revealed that when the combination of MLCNT of "Taunit" series and nanodiamonds is added to the electrolyte, the microhardness of the chromium coating increases to 1,084 kg/mm2.
Теги: carbon nanotubes chrome galvanic coating microhardness nanodiamonds наноалмазы; микротвердость углеродные нанотрубки хромовое гальваническое покрытие
CHROMIUM GALVANIC PLATING MODIFIED BY A COMBINATION OF MULTILAYER CARBON NANOTUBES AND NANODIAMONDS
М.Насрауи*, аспирант, (ORCID: 0000-0002-8152-1793) / nasraoui.mariem@gmail.com
M.Nasraoui*, Post-graduate
DOI: 10.22184/1993-8578.2021.14.3-4.206.211
Получено: 18.06.2021 г.
An experimental study of the microhardness of the obtained chromium plating from a standard electrolyte modified with a combination of multilayer carbon nanotubes (MLCNT) and nanodiamonds was carried out. It was revealed that when the combination of MLCNT of "Taunit" series (concentration of 80 mg/l) and nanodiamonds (concentration of 12 g/l) is added to the electrolyte, the microhardness of the chromium coating increases to 1,084 kg/mm2 (as compared with the chromium coating obtained from the standard chromium electrolyte without additives, the increase in microhardness is 27%).
INTRODUCTION
The earlier conducted studies have shown that the use of nanoparticles of single-layer carbon nanotubes [1], multilayer carbon nanotubes (MLCNT) of "Taunit" series [2], nanodiamonds [3] and graphene oxide [4] in chromium galvanic processes makes it possible to obtain positive results due to improving the functional properties of galvanic plating and, in particular, by increasing the microhardness and wear resistance of these platings.
It was revealed that at a concentration of single-layer carbon nanotubes of 50 mg/l the microhardness of the chromium platings increases to 858 kg/mm2 [1], at a concentration of multilayer carbon nanotubes 80 mg/l the microhardness of the chromium platings increases to 1024 kg/mm2 [2], at the concentration of nanodiamonds 12 g/l the microhardness of the chromium plating increases to 1050 kg/mm2 [3], and at a concentration of graphene oxide 10 mg/l, the microhardness of the chromium plating increases to 1064 kg/mm2 [4]. Compared to a chromium plating obtained from a standard chromium electrolyte without additives, an increase in microhardness is, respectively, 16, 20, 23 and 24%.
Based on the positive experience of applying separately nanoparticles of SLCNT and MLCNT of "Taunit" series, nanodiamonds and graphene oxide in electroplating technology, it is interesting to conduct research of the effects of their combinations on the characteristics of electroplating processes and, in particular, on the microhardness of chromium coatings.
Figures 1 and 2 show images of chromium-coated samples made on the Merlin scanning electron microscope. Fig.1 indicates the multilayer carbon nanotubes, which have penetrated into the chromium coating, and Fig.2 shows a graphene oxide plate.
The aim of the work was to study microhardness of the resulting sediment of the technological process for obtaining modified chromium plating when the combination of multilayer carbon "Taunit" series nanotubes (80 mg/l) and nanodiamonds (12 g/l) was added into the electrolyte.
RESEARCH METHODS
The chromium galvanic plating was obtained out using the most common chromium sulphate electrolyte of the following composition: chrome antihidride CrO3 – 250 g/l, sulfuric acid H2SO4 – 2.5 g/l.
In the presented work 0.1 dm2 (30 × 30 mm) square plates made of St3 steel were used as a cathode. Only the side facing the anode was covered and the reverse side was isolated.
A plate of the following composition: 10% tin and 90% lead was used as the anode. The ratio of the anode/cathode area was 1:1.
After preparation and refining of the chromium electrolyte, the chromium plating was applied from the electrolyte without additives.
Then, the chromium coating was applied from the electrolyte adding a combination of multilayer carbon nanotubes of "Taunit" series (80 mg/l) and nanodiamonds (12 g/l).
The first additive of the nanoscale material is an aqueous suspension of a diamond load containing 62 wt. % of detonation nanodiamonds (DND) [5]. Before administering to the electrolyte, the suspension was treated with ultrasound using IL 100-6/4 at frequency of 22 kHz, the intensity of the sound is 786 W/cm2 and the processing time equaled 30 minutes.
The second addition of the nanoscale material was the multilayer carbon nanotubes in the form of soluble effervescent tablets which were added to the volume of electrolyte to obtain a stable colloidal solution [6]. Carbon nanotubes were mixed with the following components: a surfactant polyvinylpyrrolidone, sodium bicarbonate and citric acid, after which they were pressed into tablets. The operating pressure was 32 kg/mm2. These agglomerates were dispersed under the action of the sodium carbon dioxide hydrocarbonate released when dissolved.
The highly dispersed metastable colloid state was achieved by the use of surfactants. Dissolution of the tablets was carried out at 55 °C for 12 hours.
In each option, the coating was applied on 5 parts. The microhardness of the resulting plating was measured using a PMT-3M hardness meter.
A PMT-3M microhardness meter is designed to measure microhardness of materials by pressing in the test material of the Vickers diamond tip with a square base of the quadruple pyramid, providing a geometric and mechanical semblance of prints as an indenter is deepened under the action of the load. The measurement of the print diagonals was performed using a FOM-1-16 photovoltaic ocular micrometer with automatic processing of measurement results. The measurement error was 2%.
On each sample, the microhardness was measured at 5 points, in which the prints where the prints were symmetrical, after which the result was averaged. The averaging was performed on all 5 parts used in the experiment.
RESULTS
The results are presented in Table 1 and Fig.3.
The results of experiments to determine microhardness of the chromium plating with adding of multilayer carbon nanotubes "Taunit" (80 mg/l) and nanodiamopnds (12 g/l) separately and their combinations are shown in Fig.3.
DISCUSSION
When the mixture of nanodiamonds is added with a concentration of 12 g/l and the multilayer carbon nanotubes "Taunit" (80 mg/l), the microhardness of the chromium plating increases to 1,084 kg/mm2.
The microhardness increased by 27% as compared with chromium plating obtained from a standard chromium electrolyte without additives. The results are not within the measurement error (which is 2% for the used instrument PMT-3).
Hence, addition of a mixture of nanodiamonds and multilayer carbon nanotubes "Taunit" allows of obtaining the microhardness that exceeds 4–7% of the values of this qualitative indicator when using nanodiamonds and multilayer carbon nanotubes "Taunit" separately.
Figure 4 shows an example of microindenting.
CONCLUSIONS
The experimental study of the microhardness of the obtained chromium electroplating coating from a standard electrolyte modified by a mixture of nanodiamonds (12 g/l) and MLCNT of "Taunit" series (80 mg/l) was carried out.
It has been experimentally established that the addition of a mixture of nanodiamonds (12 g/l) and the MLCNT "Taunit" (80 mg/l) increases the microhardness of the chromium plating. It was revealed that the highest microhardness was obtained by adding a mixture of nanodiamonds (12 g/l) and MLCNT "Taunit" (80 mg/l), the microhardness of the chromium plating increases from 853 to 1,084 kg/mm2 (compared to chromium coating, obtained from the standard chromium electrolyte without additives, the increase of microhardness is 27%).
Chromium plating with increased microhardness (and, as a result, with increased wear resistance) is of interest for use in parts subject to dynamic loads in friction mode. Lifetime of the chromium-coated parts obtained from electrolyte with a mixture of nanodiamonds (12 g/l) and the MLCNT of "Taunit" series (80 mg/l) is significantly higher than when these nanostructures are used separately or when a traditional chromium plating is used. ■
Declaration of Competing Interest. The author declares that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
М.Насрауи*, аспирант, (ORCID: 0000-0002-8152-1793) / nasraoui.mariem@gmail.com
M.Nasraoui*, Post-graduate
DOI: 10.22184/1993-8578.2021.14.3-4.206.211
Получено: 18.06.2021 г.
An experimental study of the microhardness of the obtained chromium plating from a standard electrolyte modified with a combination of multilayer carbon nanotubes (MLCNT) and nanodiamonds was carried out. It was revealed that when the combination of MLCNT of "Taunit" series (concentration of 80 mg/l) and nanodiamonds (concentration of 12 g/l) is added to the electrolyte, the microhardness of the chromium coating increases to 1,084 kg/mm2 (as compared with the chromium coating obtained from the standard chromium electrolyte without additives, the increase in microhardness is 27%).
INTRODUCTION
The earlier conducted studies have shown that the use of nanoparticles of single-layer carbon nanotubes [1], multilayer carbon nanotubes (MLCNT) of "Taunit" series [2], nanodiamonds [3] and graphene oxide [4] in chromium galvanic processes makes it possible to obtain positive results due to improving the functional properties of galvanic plating and, in particular, by increasing the microhardness and wear resistance of these platings.
It was revealed that at a concentration of single-layer carbon nanotubes of 50 mg/l the microhardness of the chromium platings increases to 858 kg/mm2 [1], at a concentration of multilayer carbon nanotubes 80 mg/l the microhardness of the chromium platings increases to 1024 kg/mm2 [2], at the concentration of nanodiamonds 12 g/l the microhardness of the chromium plating increases to 1050 kg/mm2 [3], and at a concentration of graphene oxide 10 mg/l, the microhardness of the chromium plating increases to 1064 kg/mm2 [4]. Compared to a chromium plating obtained from a standard chromium electrolyte without additives, an increase in microhardness is, respectively, 16, 20, 23 and 24%.
Based on the positive experience of applying separately nanoparticles of SLCNT and MLCNT of "Taunit" series, nanodiamonds and graphene oxide in electroplating technology, it is interesting to conduct research of the effects of their combinations on the characteristics of electroplating processes and, in particular, on the microhardness of chromium coatings.
Figures 1 and 2 show images of chromium-coated samples made on the Merlin scanning electron microscope. Fig.1 indicates the multilayer carbon nanotubes, which have penetrated into the chromium coating, and Fig.2 shows a graphene oxide plate.
The aim of the work was to study microhardness of the resulting sediment of the technological process for obtaining modified chromium plating when the combination of multilayer carbon "Taunit" series nanotubes (80 mg/l) and nanodiamonds (12 g/l) was added into the electrolyte.
RESEARCH METHODS
The chromium galvanic plating was obtained out using the most common chromium sulphate electrolyte of the following composition: chrome antihidride CrO3 – 250 g/l, sulfuric acid H2SO4 – 2.5 g/l.
In the presented work 0.1 dm2 (30 × 30 mm) square plates made of St3 steel were used as a cathode. Only the side facing the anode was covered and the reverse side was isolated.
A plate of the following composition: 10% tin and 90% lead was used as the anode. The ratio of the anode/cathode area was 1:1.
After preparation and refining of the chromium electrolyte, the chromium plating was applied from the electrolyte without additives.
Then, the chromium coating was applied from the electrolyte adding a combination of multilayer carbon nanotubes of "Taunit" series (80 mg/l) and nanodiamonds (12 g/l).
The first additive of the nanoscale material is an aqueous suspension of a diamond load containing 62 wt. % of detonation nanodiamonds (DND) [5]. Before administering to the electrolyte, the suspension was treated with ultrasound using IL 100-6/4 at frequency of 22 kHz, the intensity of the sound is 786 W/cm2 and the processing time equaled 30 minutes.
The second addition of the nanoscale material was the multilayer carbon nanotubes in the form of soluble effervescent tablets which were added to the volume of electrolyte to obtain a stable colloidal solution [6]. Carbon nanotubes were mixed with the following components: a surfactant polyvinylpyrrolidone, sodium bicarbonate and citric acid, after which they were pressed into tablets. The operating pressure was 32 kg/mm2. These agglomerates were dispersed under the action of the sodium carbon dioxide hydrocarbonate released when dissolved.
The highly dispersed metastable colloid state was achieved by the use of surfactants. Dissolution of the tablets was carried out at 55 °C for 12 hours.
In each option, the coating was applied on 5 parts. The microhardness of the resulting plating was measured using a PMT-3M hardness meter.
A PMT-3M microhardness meter is designed to measure microhardness of materials by pressing in the test material of the Vickers diamond tip with a square base of the quadruple pyramid, providing a geometric and mechanical semblance of prints as an indenter is deepened under the action of the load. The measurement of the print diagonals was performed using a FOM-1-16 photovoltaic ocular micrometer with automatic processing of measurement results. The measurement error was 2%.
On each sample, the microhardness was measured at 5 points, in which the prints where the prints were symmetrical, after which the result was averaged. The averaging was performed on all 5 parts used in the experiment.
RESULTS
The results are presented in Table 1 and Fig.3.
The results of experiments to determine microhardness of the chromium plating with adding of multilayer carbon nanotubes "Taunit" (80 mg/l) and nanodiamopnds (12 g/l) separately and their combinations are shown in Fig.3.
DISCUSSION
When the mixture of nanodiamonds is added with a concentration of 12 g/l and the multilayer carbon nanotubes "Taunit" (80 mg/l), the microhardness of the chromium plating increases to 1,084 kg/mm2.
The microhardness increased by 27% as compared with chromium plating obtained from a standard chromium electrolyte without additives. The results are not within the measurement error (which is 2% for the used instrument PMT-3).
Hence, addition of a mixture of nanodiamonds and multilayer carbon nanotubes "Taunit" allows of obtaining the microhardness that exceeds 4–7% of the values of this qualitative indicator when using nanodiamonds and multilayer carbon nanotubes "Taunit" separately.
Figure 4 shows an example of microindenting.
CONCLUSIONS
The experimental study of the microhardness of the obtained chromium electroplating coating from a standard electrolyte modified by a mixture of nanodiamonds (12 g/l) and MLCNT of "Taunit" series (80 mg/l) was carried out.
It has been experimentally established that the addition of a mixture of nanodiamonds (12 g/l) and the MLCNT "Taunit" (80 mg/l) increases the microhardness of the chromium plating. It was revealed that the highest microhardness was obtained by adding a mixture of nanodiamonds (12 g/l) and MLCNT "Taunit" (80 mg/l), the microhardness of the chromium plating increases from 853 to 1,084 kg/mm2 (compared to chromium coating, obtained from the standard chromium electrolyte without additives, the increase of microhardness is 27%).
Chromium plating with increased microhardness (and, as a result, with increased wear resistance) is of interest for use in parts subject to dynamic loads in friction mode. Lifetime of the chromium-coated parts obtained from electrolyte with a mixture of nanodiamonds (12 g/l) and the MLCNT of "Taunit" series (80 mg/l) is significantly higher than when these nanostructures are used separately or when a traditional chromium plating is used. ■
Declaration of Competing Interest. The author declares that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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