Communications in Science and Technology 10.
17Ae28
COMMUNICATIONS IN
SCIENCE AND TECHNOLOGY
Homepage: cst.
Rotating speed and magnetic pole dependency assisted on copper deposition onto aluminum alloy substrate for bacterial eradication Basoria,*.
Ruliyantab.
Maman Kartaman Ajiriyantoc.
Rosika Kriswarinic.
Heri Hardiyantic.
Cahaya Rosyidand.
Sigit Dwi Yudantoe.
Evi Ulina Margareta Situmorangf.
Daniel Edbertg.
Dwi Nantoh.
Ferry Budhi Susetyoi Department of Mechanical Engineering.
Universitas Nasional.
Jakarta 12520.
Indonesia Department of Electrical Engineering.
Universitas Nasional.
Jakarta 12520.
Indonesia Research Center for Nuclear Material and Radioactive Waste Technology.
National Research and Innovation Agency.
Banten 15314.
Indonesia Department of Petroleum Engineering.
Universitas Trisakti.
Jakarta 11440.
Indonesia Research Center for Metallurgy.
National Research and Innovation Agency.
Banten 15314.
Indonesia Department of Physiology School of Medicine and Health Sciences.
Atma Jaya Catholic University of Indonesia.
Jakarta 14440.
Indonesia Department of Microbiology.
Atma Jaya Catholic University of Indonesia.
Jakarta 14440.
Indonesia Department of Physics Education.
UIN Syarif Hidayatullah.
Jakarta 15412.
Indonesia Department of Mechanical Engineering.
Universitas Negeri Jakarta.
Jakarta 13220.
Indonesia Article history:
Received: 26 September 2024 / Received in revised form: 27 January 2025 / Accepted: 21 February 2025 Abstract Copper (C.
is widely used in many sectors, such as drinking water piping, heat exchangers, and medical equipment.
The present research conducted an electrodeposition of Cu over an aluminum (A.
alloy substrate under the influence of various magnetic poles and rotating speeds.
In the present study, a number of investigations, including deposition rate, current efficiency, coating thickness, surface morphology and phase, crystallographic orientation, antibacterial activity, electrochemical behavior, and hardness test were conducted.
Increasing the rotation speed promoted to enhanced deposition rate and current efficiency for both magnetic poles influence.
An increase in the deposition rate from 83 to 13.
67 AAm/h led to the increasing thickness, a change in surface morphology near the spheroidal, becoming a faceted structure.
Presenting and rising in the rotation of a magnetic field led to a reduced surface roughness and crystallite size of Cu film for both magnetic poles influence.
The Cu film made without spinning magnetic had a characteristic of highest bacterial inhibition zone around 2.
50 A0.
56 cmA.
The CuRN50 sample had the lowest corrosion rate at around 0.
055 mmpy, while the CuRS100 sample had the highest hardness value at 72 HV for having the lowest crystallite size.
Cu coated onto Al alloy could enhance its properties, such as being antimicrobial, being resistant against corrosion and having the hardness value.
Keywords: North and South Pole.
SEM-EDS.
XRD.
electrochemical behavior.
Introduction Copper (C.
due to its promising properties is widely used in many sectors, such as drinking water piping, heat exchangers, and medical equipment .
Ae.
As film, it has a higher performance to kill bacteria compared to bulk Cu .
Additionally, coated onto aluminum (A.
Cu could enhance its properties, such as being antimicrobial, being resistant against corrosion and having hardness value .
Coating synthesis can be conducted by means of * Corresponding author.
Email: basori@civitas.
https://doi.
org/10.
21924/cst.
electrochemical, spin coating, or spray methods .
Ae.
In view of its simplicity and affordability, the electrodeposition is seen as a more suitable method for coating Cu onto Al alloy .
Cu electrodepositions attract many researchers to investigate the formed Cu films.
Brands et al.
investigated the structure, surface morphology, electrical, optical, and magnetic properties of electrodeposited Cu2O .
Antenucci et al.
he mechanical and thermal propertie.
of open-cell Al foams through Cu electrodeposition .
Augustin et al.
investigated the effect of current density at Cu electrodeposition on the microstructure, hardness, and antibacterial activity of Cu for antimicrobial Al touch application .
Furthermore.
Kuisor et al.
fabricated CuO film using electrodeposition in which the film was tested for This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.
0 license Basori et al.
/ Communications in Science and Technology 10.
17Ae28 antibacterial activity using Staphylococcus aureus (S.
that successfully reduced the bacterial colony during the experiment .
Isa et al.
performed electrodeposition Cu over 304 stainless steels in which a coated sample was tested for antibacterial properties.
In a 10-minute exposure to the coated sample, it could successfully achieve a 100 % reduction of S.
Many factors, including magnetic field, determine the formed Cu films when electrodeposition is performed.
The existing magnetic field at the electrodeposition process can appear to have several forces.
The Lorentz force acts on a moving ion in the solution, resulting in convection flow .
The effects of the magnetic field may also relate to the electrokinetic-magnetohydrodynamic (MHD) effect resulting in the body force acting in the diffuse layer .
Another force caused by the magnetic field is paramagnetic gradient force .
that causes the movement of magnetic ions in the diffusion layer.
Another possible force is a magnetic gradient It acts on paramagnetic and diamagnetic ions .
general, introducing a magnetic field during the electrodeposition process leads to the arrangement of moving ions towards the cathode.
In view of many forces exhibited by presenting a magnet, the investigations of several researchers have been focused on unrotated magnetic field-induced Cu electrodeposition .
,18Ae.
Investigating the electrodeposition of Cu under 15 T of magnetic field.
Miura et al.
found extraordinary dendritic growth .
Murdoch et al.
conducted an electrodeposition of Cu using the influence of 0.
25 and 0.
5 T placed on the working electrode's reverse, and this resulted in the lowest thickness when influencing 0.
25 and 0.
5 T with the south pole rather than the north pole .
Sudibyo et al.
conducted the electrodeposition of Cu using the influence of 300 and 900 G .
eodymium magne.
, resulting in higher grain when electrodeposition Cu using the influence of 900 G .
Yin et investigated anomalous Cu hydride phase during the magnetic field-assisted electrodeposition of Cu.
Presenting an anti-parallel magnetohydrodynamic effect could enhance the hydrogen evolution and result in poor film quality .
Kovalyov et al.
found that a weak magnetic field .
5 and 0.
7 mT) could affect the electrodeposition process, surface morphology, and texture .
Liu et al.
stated that magnetic field-assisted electrodeposition could change hydrogen bond structure, reduce the charge transfer resistance, and increase the electrolyte viscosity .
Due to its ability to enhance the properties of films, electrodeposition assisted with a spinning magnetic field is considered to attract several researchers.
Wang and Chen used 18 T of a magnetic field with various rotating speeds .
03000 rp.
when electrodeposition of nickel (N.
and results presenting a magnetic field with various rotating speeds could decrease surface roughness .
Ji et al.
fabricated Ni-SiC using an electrodeposition process and found that the exhibited rotating magnetic field made SiC particle distribution more uniform .
Syamsuir et al.
stated that presenting a rotating magnetic field .
and 800 rp.
at electrodeposition process could make surface morphology of the film more uniform .
They found that increasing the rotating speed of a magnetic field .
ne piece of neodymium magnet arranged spread five parts in the upside Teflo.
at electrodeposition process could transform surface morphology from spheroidal to faceted structure .
Oxygen content on the Cu film surface can disrupt the transformation of Cu to Cu ions, reducing antibacterial performance .
The formation of surface morphology can have an impact on the antibacterial performance.
Surface morphology, such as spheroidal and faceted structures, also contributes to the inhibition zone.
A Cu film with spheroidal coating tends to create a higher inhibition zone .
The use of a magnetic field during electrodeposition can determine the movement of ions towards the cathode surface.
Adjusting magnetic field rotation during electrodeposition also determines the ion movement.
Furthermore, the different poles of the selected magnet also influence ion movement at electrodeposition process.
Generally, the speed of ion movement can affect the properties of formed film.
Based upon the literature review above, higher rotation was used (C 500 rp.
to influence the electrodeposition.
for this, the present study used the speed rotation of 50 and 100 rpm.
The speed rotation was chosen on the basis of previous study conducting Cu electrodeposition by means of barreling apparatus .
Syamsuir et al.
used one piece of neodymium magnet arranged to spread five parts in the upside Teflon .
Therefore, the present research used more neodymium magnets to result in more influence of the magnetic field.
Here, the influence of spinning using different magnetic poles was also not considered.
Murdoch et al.
found that different magnetic poles influenced the deposition process, resulting in different surface morphologies in Cu films .
Therefore, the present research comprehensively investigated the influence of the rotating speed and magnetic pole during Cu electrodeposition on the formation of the film for bacterial eradication applications.
The electrodeposition of Cu was determined by various magnetic poles .
orth and sout.
and magnetic rotating speeds .
, 50, and 100 rp.
Several investigations were conducted using digital scales, scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS).
X-ray diffraction, digital camera, optical microscope, potentiostat dan Vickers hardness.
Materials and Methods Materials Al alloy .
106 wt.
% Si, 0.
365 wt.
% Fe, 0.
055 wt.
% Cu, 043 wt.
% Mn, 0.
030 wt.
% Mg, 0.
003 wt.
% Zn, 0.
002 wt.
Ni, 0.
018 wt.
% Ti, 0.
003 wt.
% Pb, and Al balanc.
was used as cathode, while pure Cu was used as anode.
Electrolyte solution was prepared by dissolving CuSO4.
5H2O (Merc.
in deionized water.
Electrolyte solution .
ml of volum.
was used for electrodeposition with the composition of 0.
CuSO4.
5H2O plus 20 ml of H2SO4.
Sample preparation It began by cutting Al alloy into 2 C 2 cm for electrodeposition substrate using a shearing machine.
Cu film was then made using a DC power supply (MDB PS-305DM) with 40 mA, and at 25CC, and pH 5.
5 for one h.
Cu films were Basori et al.
/ Communications in Science and Technology 10.
17Ae28 prepared under the influence of a clockwise rotating magnetic field, as seen in Fig.
The plating bath was placed on top of the rotation magnetic field equipment.
Two pieces of neodymium magnet were stacked and arranged .
ix part.
in the upside Teflon, as seen in Fig.
One piece of neodymium magnet had 0.
08 T of intensity .
easured using gauss meter TD-8.
Five variation samples were made.
one sample was made without the influence of a rotating magnetic field as a The sample was made by influencing 50 rpm and 100 rpm.
Different pole variations were also used.
Table 1 depicts the complete sample names.
Table 1.
Sample name and remark Sample name CuR0 Remark without the influence of a rotating magnetic field CuRN50 50 rpm, north pole near the substrate CuRN100 100 rpm, north pole near the substrate CuRS50 50 rpm, south pole near the substrate CuRS100 100 rpm, south pole near the substrate specimen was removed from the plate using sterile forceps.
The agar was re-incubated at 35CC A2 for 24 hours to observe the antimicrobial activity post-contact.
The oxides of the metal formed before and after the test were observed by means of Olympus CX23 microscope under an 180 C any changes inside of the agar plate were In addition, the observations of microbial reduction test were conducted .
ithin 1, 2, 4, 6 and 12 .
The electrochemical test was conducted using Ossila potentiostat in 0.
9 % NaCl .
oom temperatur.
Prior to the electrochemical test.
Cu films were mounted and left open area for 1 C1 cm2.
Here.
Cu films were used as working electrode.
Ag/AgCl and Pt wire were used as reference electrode and counter electrode, respectively.
There are two kinds of test in electrochemical behavior measurement, those are open circuit potential (OCP) and potentiodynamic OCP is performed until 1200 seconds, while potentiodynamic polarization is performed from -1 to -0.
using 5 mV/s of scan rate.
The potentiodynamic polarization data was analyzed through the Tafel extrapolation method to find Icorr and Ecorr.
Afterward, corrosion rate could be calculated using following equation .
Corrosion rate .
= K (.
Icor.
D)) .
where K is constant .
00327 mmp.
, a is atomic weight.
Icorr is corrosion current density .
/cmA), n is the number electron involved, and D is Cu density .
/cmA).
The hardness test was performed using Future-Tech (FV300.
Vickers hardness tester.
Five repeatable measurements were conducted over Cu layer by using 1 kg of load.
Results and Discussion Deposition rate and current efficiency Fig.
Rotation magnetic field equipment Characterizations The deposition rate and current efficiency were measured similar to previous studies .
Thermo Scientific SEM-EDS was used to investigate surface morphology and elements.
The cross section was also investigated using SEM apparatus to measure Cu layer thickness.
According to SEM image.
Image J software was used to measure grain distribution and the roughness of Cu film.
Meanwhile.
X-ray diffraction was conducted using PANalytical (Cu K radiatio.
with step size 02C and refined with the help of GSAS software .
Similarly, antibacterial activity was investigated according to previous studies .
The assessment of microbial reduction of various samples was adapted from ISO 22196 for nonporous material.
aureus ATCC 25923 was used in this test.
The inhibition zone was documented using a digital camera and assessed using an unaided eye and the area of inhibition was measured by Image J software.
Each measurement was performed five times to ensure the data homogeneity.
The diffusible area was calculated by subtracting the area of inhibition from the metal size.
One-way ANOVA analysis was conducted to investigate whether there was significance between the polarities of the magnets.
Moreover, the Fig.
2 shows the deposition rate and current efficiency of electrodeposition Cu over an Al alloy substrate.
They had similar tendencies.
an increase in magnet rotation speed led to a rise in deposition rate and current efficiency.
Fig.
Deposition rate and current efficiency of Cu electrodeposition In the process of Cu electrodeposition, the oxidation process occurs at the anode and a reduction process occurs at the cathode.
An Al alloy .
to be plated is placed at Basori et al.
/ Communications in Science and Technology 10.
17Ae28 the cathode.
When the current is applied, the Cu ions are depleted in the surroundings of the cathode, making a diffusion film upper around the cathode.
Hydrogen evolution is known to occur at the cathode during Cu electrodeposition from aqueous solutions .
Less hydrogen evolution can increase the deposition rate and current efficiency because hydrogen evolution is able to disturb the movement of the ions to the cathode .
Presenting an anti-parallel magnetic field .
orth pol.
affecting the MHD effect could enhance the hydrogen evolution, decrease current efficiency, and result in poor film quality .
As shown in Fig.
hydrogen evolution seemed to influence the electrodeposition process when being determined by the north pole.
Therefore, the electrodeposition process had a lesser current efficiency than the electrodeposition process when being influenced by the south pole.
Cu films made and influenced by the rotating south pole magnet has a higher deposition rate due to the magnetic field, which was parallel to the current direction and attracts more Cu ions onto the Al alloy surface .
Rotating the magnet under the electrolyte solution during the electrodeposition process could induce an Eddy electric field .
that can act as an additional MHD flow convection effect .
Moreover, increasing the rotation speed could attract more Cu ions onto the Al alloy surface, consequently increasing the deposition rate and current efficiency.
Fig.
Thickness of various Cu layers: .
CuR0.
CuRN50.
CuRN100.
CuRS50.
CuRS100 Average thickness Fig.
3 and Fig.
4 show the thickness of various Cu layers and average thickness of Cu layers.
Compared to the average thickness to the deposition rate (Fig.
, there was a correlation between them.
Increasing the deposition rate led to an increase in the average of Cu layers thickness, similar to the study by Syamsuir et al.
Furthermore, it seemed that average coating thickness was higher than thickness found by calculating from deposition rate.
For example, average coating thickness of CuR0 sample ideally is 12.
83 AAm due to deposition sample for one hour.
Unfortunately, average coating thickness of CuR0 sample was 27.
17 AAm.
This behavior was probably due to the SEM cross section being conducted on an area near the anode .
ed arrow Fig.
According to Yang et al.
, the end area of the cathode results in higher thickness compared to the middle area .
Therefore, average thickness is higher than deposition rate value.
SEM-EDS and roughness Fig.
5 shows the SEM result and the grain distribution of various Cu film surfaces.
Samples were made by influencing the north pole magnetic field, which had a larger grain size than samples created by affecting the south pole of a magnetic Generally, presenting the south pole magnetic field influence can lead to a decrease in grain size.
While presenting south pole magnetic field influence can lead to an increase in grain size as in line with previous study .
Murdoch et al.
stated that different poles are used to influence deposition process that will result different grain size .
Moreover.
Lin et al.
stated that deposition time contributes to the formed grain size .
Fig.
Cu layers average thickness As shown in Fig.
5, the Cu sample was made with no spinning magnetic influence, leading to the formation of morphology near the spheroidal.
Cu samples made with spinning magnetic assistance led to the formation of faceted structure morphology .
Moreover, the transformation from spheroidal to faceted structure was determined by the deposition rate.
A higher nucleation rate leads to a higher deposition rate, resulting in a variation in surface morphology .
Samples made with influences from the north pole magnetic field had a low nucleation rate.
Hence, it had wider grain sizes than samples by influencing the south pole magnetic field .
Moreover, an increase in the deposition rate from 12.
83 to 13.
67 AAm/h led to a change in surface morphology near the spheroidal becoming faceted structure.
The deposition rate between 13.
67 and 14.
51 AAm/h resulted in a faceted structure of surface morphology.
The south pole had an affecting magnetic field parallel to the current direction.
Cu ions were more attracted to the Al alloy surface.
In contrast, the north pole had an affecting magnetic field that was anti-parallel to the current direction, reducing Cu ions' attraction onto the Al alloy Basori et al.
/ Communications in Science and Technology 10.
17Ae28 Moreover.
Lorentz's forces rotated opposite each other on top of the surface specimen for different magnetic This condition affected the sample film by influencing the South Pole to be smoother than the North Pole.
Ji et al.
stated that presenting a rotating magnetic field during electrodeposition can make surface morphology more uniform .
In this case, the paramagnetic force has a similar tendency for different magnetic poles.
Therefore, influencing surface morphology could be neglected.
As shown in Fig.
6, the spinning magnetic-assisted running at 50 rpm led to oxygen formed on the Cu surface.
Moreover, enhanced magnetic rotation led to a decrease or disappearance of oxygen.
Presenting oxygen on Cu film is one of the unique cases in which oxygen can be formed due to both a secondary reaction on the anode and sample storage and transport .
Fig.
7 presents the roughness analyzed result from the SEM image using ImageJ software.
CuR0.
CuRN50.
CuRN100.
CuRS50, and CuRS100 samples had a surface roughness of 62, 18.
00, 17.
38, 18.
60, and 16.
58 AAm, respectively.
Presenting a magnetic field rotation during electrodeposition led to a decrease in the surface roughness of Cu film.
More rotation could also decrease surface roughness, which is perfectly in line with the previous study .
Wang and Chen found that presenting a magnetic field during electrodeposition with various rotating speeds could decrease surface roughness .
This behavior is probably due to additional MHD flow, which is in line with the deposition rate result and could enhance the Cu ions' movement.
A higher deposition rate would result in a higher nucleation rate, consequently producing a smooth surface morphology.
Moreover, the sample made by north pole magnet influence had more roughness than sample made by north pole magnet.
This behavior probably due to MHD effect that could enhance the hydrogen evolution and result in more roughness .
X-ray diffraction Fig.
SEM and grain distribution of Cu layers: .
CuR0.
CuRN50.
CuRN100.
CuRS50.
CuRS100 Fig.
8 shows the diffraction patterns of samples of Cu deposition on substrates consisting of Al alloy plates.
The five samples were identified to have Cu phase peaks at the indexed plane peaks .
, .
, .
, .
, and .
at angles 2 = 43.
31, 50.
45, 74.
13, 89.
94, and 95.
The cubic crystal system was found in the Cu phase, and it had a space group of fm-3m.
The cubic Cu phase peaks at these angles were found consistent with the findings from studies by Omar and Francisco Briones et al.
This demonstrated that the procedure for depositing Cu on Al alloy plates has been successfully completed.
At the indexed plane peaks .
, .
, .
, .
, and .
of the five diffraction patterns, they were also found on the Al alloy plate substrate along with the copper phase.
Xu et al.
and Ayieko et al.
standard Al diffraction pattern identical to this peak of Al .
The mean crystallite size and lattice value of the five deposition samples were compared to further analyze the diffraction pattern.
The Rietveld method was employed to determine the lattice of the five samples.
The cubic Cu phase lattice of all five samples was measured at 0.
3615 nm based upon the calculation results.
Changes in magnetic poles and rotating speed showed no effect on the lattice value of the cubic Cu phase.
Table 2 presents the data from the crystallographic calculation.
To determine the mean crystallite size, the Williamson-Hall plot method was utilized.
contrast to the lattice value, the mean crystallite size was affected by the rotating speed and poles.
The mean crystallite size became finer with the increase in magnet rotation speed perfectly matched with surface roughness analysis.
Basori et al.
/ Communications in Science and Technology 10.
17Ae28 Fig.
EDS Cu layers: .
CuR0.
CuRN50.
CuRN100.
CuRS50.
CuRS100 Basori et al.
/ Communications in Science and Technology 10.
17Ae28 Table 2.
Crystallographic data calculated from various samples Source CuR0 CuRN50 CuRN100 CuRS50 CuRS100 Name: Copper (C.
Phase Space group: F m -3 m .
Crystal system: cubic Lattice .
wRp (%) GoF Mean size .
Microstrain (%) Antibacterial activity Fig.
9 describes the antibacterial activity test after 24 hours of contact.
Material placement in the middle of Mueller Hinton agar was inoculated with S.
aureus ATCC 25923.
Noticing the inhibition zones around the material.
calculation is presented in Table 3.
The metal ions were diffused into the agar to inhibit the growth of S.
Fig.
Roughness Cu layers: .
CuR0.
CuRN50.
CuRN100.
CuRS50.
CuRS100 Fig.
X-ray diffraction pattern of various sample Fig.
Antibacterial activity test after 24 hours: .
CuRN50.
CuRN100.
CuR0.
CuRS50.
CuRS100 Cu, particularly in the form of metal-organic frameworks (MOF.
and nanoparticles, exhibited significant antibacterial activity against Gram-positive bacteria such as S.
The peptidoglycan layer in Gram-positive bacteria plays a significant role in their susceptibility to Cu although its direct interaction with Cu is not as straightforward as with other antimicrobial agents.
Cu is able to induce modifications in the peptidoglycan layer, such as increased cross-linkage, which can affect the overall structure and function of the cell wall.
These modifications can either enhance or reduce the susceptibility of Gram-positive bacteria to Cu, dependent on the specific bacterial strain and environmental conditions .
In this research, the Cu induced contact killing.
The antimicrobial activity of Cu is believed to involve contactmediated killing, initiating membrane degradation.
The susceptibility of Gram-positive strains to Cu is attributed to the thick peptidoglycan layer, reducing cell wall permeability to other metal ions, including Zinc .
Basori et al.
/ Communications in Science and Technology 10.
17Ae28 As shown in Fig.
9, the inoculum was totally annihilated by electroplated materials.
The log reduction was not calculated due to the total killing of the bacteria.
However, the total reduction of > 105 CFU/ml might suggest a percentage reduction of > 99.
999% .
ee Table .
Moreover, there was a zone of inhibition between the sample and bacterial lawn that was also visible inside the zoneAos white crystals and some bluish color change inside the agar.
This suggests that the Cu material diffused and interacted with the agar can result in a zone of bacterial growth inhibition.
As seen in Table 3, the widest diffusion zone was observed in CuR0 with the zone of diffusion and inhibition areas of 99 cm2 and 2.
5 cmA.
This was statistically significant with p < 0.
001 (ANOVA.
CI 95%).
Also, there was significance in independent T-Test analyses between CuR0 and CuR50 group .
< 0.
CI 95%).
R0 and R100 group .
< 0.
CI 95%),
and between CuR50 and CuR100 Group .
< 0.
CI 95%).
To investigate whether there was significance between the polarities of the magnets, independent T-test analyses were There was no significant difference in the outcome between the south pole group and the north one .
=0.
95%).
Moreover, there were no inhibitions in the blank group, and the bacteria grew underneath the metal.
Comparing to the previous study, less inhibition was found in the present study .
This behavior was probably due to higher crystallite size form in the all samples .
Previous study found crystallite size between 95.
66 and 100.
50 nm .
While in the present study, the crystallite size of Cu layer was between 126 and 308 nm.
Ramyadevi et al.
and Ahmed et al.
in their studies, when testing Cu nanoparticle for antibacterial activity using S.
aureus, found the inhibition zone of 2.
2 cm and 2.
4 cm .
The release of Cu ions inside of the agar was lethal towards S.
As shown in Fig.
CuR0 surface morphology formed near to spheroidal, while other samples formed a faceted structure.
In Table 3, it can be seen that higher inhibition zone was seen in CuR0 sample.
Therefore, it can be concluded that the spheroidal form results in the higher inhibition zone compared to faceted structure, which is perfectly in agreement with previous study .
This condition probably occurred due to the spheroidal structure having a wider surface area than the faceted structure, where more Cu ions were released.
Moreover, an increase in rotation leads to a decrease in Several researchers have found that roughness is independent of the inhibition zone, which aligns with the present study .
Moreover, the generation of reactive oxygen species (ROS) and damage to cell membranes are the main ways in which metals' broad antibacterial potential has been extensively studied .
Ae.
Even so, metals can target particular cellular components and, when combined, are likely to improve pathogen clearance despite their non-specific activity.
Conversely.
Cu has an ability to change metabolic pathways in addition to cause damage to DNA and cell membranes through the generation of ROS .
The combined mode of action has not been investigated so far, despite the fact that the modes of action of various metal ions have been well The variability in antimicrobial efficaciousness between various combinations can be explained by the diverse chemical reactivity of metal ions with bacterial cells and their specific biological targets .
Table 3.
The reduction of colony, and diffusible metal observation Microbial reduction Sample Final load (CFU/m.
Zone of .
mA) Inhibition area .
mA) Blank 01 A0.
48 A0.
CuR0 99 A0.
50 A0.
21 A0.
61 A0.
00 A0.
89 A0.
CuRS50 16 A0.
73 A0.
CuRS100 17 A0.
14 A0.
CuRN50 CuRN100 Initial load (CFU/m.
Diffusible metal
5 C 105
The use of magnetic rotation during material synthesis showed a significant impact on the results.
Materials synthesized without magnetic rotation (R.
showed the stronger antibacterial effects compared to those synthesized at 50 rpm or 100 rpm.
However, increasing magnet rotation significantly enhanced the size of the inhibition zone.
As a result, the inhibition zone at 100 rpm was found larger than that of at 50 rpm.
This condition was probably due to forming some oxygen on the Cu films surface as seen in EDS result, which could disrupt transformation Cu to be Cu ions.
Qu et al.
found that antibacterial behavior was determined by Cu ions Fig.
After 24 hours of post contact test: .
CuRN50.
CuRN100.
CuR0.
CuRS50.
CuRS100 Fig.
10 shows the results after 24 hours of post-contact The inhibitory zones appeared after the removal of the There were some metal infiltrations inside the agar on every plate making the agar cracked.
This indicated gasforming or exothermic reaction inside the agar, increasing the antimicrobial ability of the material .
There were no antiStaphylococcal effects on the blank material.
therefore, there was a regrowth of microorganisms in the place where the metal was previously placed.
Fig.
11 shows antibacterial activity pretest microscope observation, and Fig.
12 shows antibacterial activity post-test microscope observation.
The microscopic observation of electroplated surfaces occurred under an 180 C magnification Basori et al.
/ Communications in Science and Technology 10.
17Ae28 optical microscope.
There was a significant proportion in the formation of white crystals on the electroplated surface after The crystals did not form on the surface of the blank.
The Cu formed oxides, which changed the surface color.
MarkoviN et al.
stated that color change in the Cu is in relation to adsorption or reduction Cu ions .
were conducted.
At 6 hours of investigation.
CuR0 sample resulted in a reduction colony-forming units per milliliter around 104, which was in line with inhibition area value .
igher inhibition are.
While other samples still showed similar results when initial exposure occurred (See Table .
Table 4.
Microbial reduction assessment of Cu samples Sample CuR0
>105
>105
CuRN50
>105
CuRN100
>10
CuRS50
CuRS100
>105
>105
>105
>105
>105
>10
>10
>10
>105
>105
>105
>105
>105
>105
>105
(CFU/m.
>10 >10 >10 >10 Electrochemical behavior Fig.
Antibacterial activity pretest microscope observation: .
CuRN50.
CuRN100.
CuR0.
CuRS50.
CuRS100 Fig.
Antibacterial activity post-test microscope observation: .
CuRN50.
CuRN100.
CuR0.
CuRS50.
CuRS100 Fig.
14 shows the OCP measurement result of various Cu EOCP values of the CuR0.
CuRN50.
CuRN100.
CuRS50, and CuRS100 were -0.
643, -0.
667, -0.
658, -0.
641 V vs Ag/AgCl, respectively.
Previous study found EOCP of Cu layer over Al alloy between -0.
694 and -0.
vs Ag/AgCl .
All samples showed a shift to more negative value to reach a steady state.
TasiN et al.
stated that this condition implies the Cu oxide dissolution and CuCl layer formation .
The CuRN50 layer seemed more stable than other sample, showing to reach steady state at around 600 s for OCP measurement.
Fig.
15 represents potentiodynamic polarization test result 9 % NaCl.
Table 4 presents the tafel extrapolation result.
Using Eq.
, corrosion rate was calculated and summarized in Table 5.
As shown in Table 5, the CuRN50 sample was found as the sample with the lowest corrosion rate, probably due to the highest oxygen on the Cu surface that could form an oxide .
Narayanan et al.
stated that oxygen content in the Cu film would be an obstacle for chloride ions to adsorb in the film .
Therefore, the oxide could result in better protection from aggressive species in the 0.
9 % NaCl medium.
Moreover, compared to Fig.
6, the oxygen content of the Cu layer was linear to the corrosion rate.
Higher oxygen content led to decrease corrosion rate.
Fig.
Microbial reduction test observation: .
CuR0.
CuRN50.
CuRN100.
CuRS50.
CuRS100 As seen in Fig.
13 and Table 4, to deep explore microbial reduction assessment, investigating at 1, 4, 6, 8, and 12 hours Fig.
OCP test curve Basori et al.
/ Communications in Science and Technology 10.
17Ae28 Conclusion Fig.
Potentiodynamic polarization test curve Table 5.
Tafel extrapolation result and corrosion rate
Sample Ecorr
(V) vs Ag/AgCl Icorr
(A/cmA) 27 C 10-5
CuRN50
78 C 10
CuRN100
77 C 10-6
CuRS50
56 C 10
CuRS100
14 C 10-5
CuR0 Corrosion rate .
Hardness test Fig.
16 represents average hardness test result using 1 kg of The hardness test was conducted with five repeatable measurements on top of Cu layer.
The average hardness in the present study varied between 47.
92 and 80.
72 HV.
Ghosh et found that Cu layer hardness from 22.
9 to 114.
7 HV .
Previous study also found Cu layer hardness between 72.
26 HV .
Moreover.
Augustine et al.
stated that hardness value is dependent on the crystallite size.
The lowest crystallite size promoted to resulting higher hardness .
Comparing Fig.
16 to Table 2, there was a linear correlation between hardness and crystallite size.
Highest hardness value was seen at CuRS100 sample, while smallest one was found at CuR0 sample.
This study has successfully conducted the Cu films fabricated under a spinning magnetic field with various rotation speeds and a magnetic pole.
Higher rotation speed was promoted to enhance deposition rate and current efficiency for both magnetic poles.
The Cu sample fabricated with no spinning magnetic influence led to the morphology formed near the spheroidal.
Cu samples made with spinning magnetic influence led to the morphology formed near the faceted structure.
Magnetic-assisted spinning at 50 rpm led to oxygen formed on the Cu surface for both magnetic poles and enhanced rotation.
This then led to the decrease or disappearance of oxygen.
Presenting and rising in magnetic field rotation led to decreased surface roughness and crystallite size of Cu film for both magnetic poles.
The Cu sample made without spinning magnetic fields influence had the highest inhibition zone size, probably due to the absence of oxygen on the Cu film surface and the morphology near the The oxygen content of the Cu layer was found linear to the corrosion rate.
Higher oxygen content led to decrease corrosion rate, while the lowest crystallite size promoted to higher hardness.
Overall.
Cu films successfully covered Al alloy and could transform it into antibacterial For future study, it is recommended to conduct the electrodeposition of Cu with spinning magnetic influence higher than 100 rpm.
Acknowledgements This study has been supported by the Ministry of Education.
Culture.
Research, and Technology through grand
funding Penelitian Fundamental-Regular with contract
087/LPPM-UNAS/VI/2024
815/LL3/AL.
04/2024.
References