Concentration Of Carbonyl Iron Particles Research Articles

Multi‐physical honeycomb metastructure fabricated by fused deposition modeling with broadband radar absorption and mechanical resistance for drones

AbstractComplex structural configuration design is necessary for dielectric‐magnetic lossy composites to achieved broadband microwave absorption in civil and defense applications. Based on the unique space filling characteristic of fractal structure, the honeycomb metastructure can possess microwave absorption and mechanical resistance. However, traditional molding technique was difficult to realize complex shape of metastructure. Herein, the dielectric‐magnetic filament with different concentration of carbonyl iron particles was fabricated by high‐temperature extrusion process. The multi‐physical honeycomb metastructure with gradient layers was printed by fused deposition modeling (FDM) in a large size. The printed dielectric‐magnetic samples exhibited strong dielectric‐magnetic loss with high printing quality. The honeycomb metastructure achieved broadband microwave absorption in the −10 dB bandwidth of 9.6–18 GHz with tensile strength of 31 MPa. The results indicate that FDM is useful to fabricate metastructure with complex shape for broadband microwave absorption. The dielectric‐magnetic properties of filament are magnified by metastructure design. The proposed design‐fabrication process is promising for functional structure realization with complex shape in the future.Highlights1. Magnetic filament was fabricated for functional 3D printing.2. Structural magnetic dissipation mechanism for microwave was presented.3. Magnetic metastructure was designed and printed for broadband absorption.4. Integrated design of mechanical and electromagnetic function was presented.5. Structural absorption effect of honeycomb metastructure was revealed.

Research on influence of polishing fluids parameters on processing effects in reciprocating magnetorheological polishing

PurposeThis paper aims to study the influence of the different parameters of magnetorheological polishing fluids (MRP fluids) on the surface roughness and material removal rate (MRR) of the workpiece surface in the reciprocating magnetorheological polishing (RMRP) process.Design/methodology/approachA series of single-factor experiments are performed to evaluate the influence of the concentration of magnetic particles, concentration of abrasive particles and size of abrasive particles on surface processing effects by using the RMRP method. Moreover, the yield stress and viscosity of MRP fluids are studied based on the Bingham plastic model by varying the MRP fluids parameters.FindingsA reasonable parameter of MRP fluids is crucial to the surface roughness and MRR of the workpiece surface, and the optimized parameters are obtained by the single-factor experiments of RMRP. The results are when the concentration of carbonyl iron particles is 40 Vol.%, the concentration of CeO2 is 5 Vol.% and the size of CeO2 is 2.5 µm in the MRP fluids, the surface roughness of the workpiece remarkably decreases to 28 nm from the initial 332 nm and the MRR of the workpiece increases to 0.118 mg/min.Originality/valueIn this study, the single-factor experiments for the different parameters of MRP fluids are studied to polish K9 glass by using the RMRP device, and the yield stress and viscosity of MRP fluids are investigated by rheological experiments, which provides reference for a reasonable selection of the MRP fluids parameter in RMRP process.

Magnetostriction Enhancement in Midrange Modulus Magnetorheological Elastomers for Sensor Applications

Magnetorheological elastomer (MRE), which is capable of exhibiting magnetostriction in the presence of a magnetic field, has a great potential to be used for the development of sensor devices. Unfortunately, to date, many works focused on studying low modulus of MRE (less than 100 kPa) which can hamper their potential application in sensors due to short lifespan and low durability. Thus, in this work, MRE with storage modulus above 300 kPa is to be developed to enhance magnetostriction magnitude and reaction force (normal force). To achieve this goal, MREs are prepared with various compositions of carbonyl iron particles (CIPs), in particular, MRE with 60, 70 and 80 wt.% of CIP. It is shown that both the magnetostriction percentage and normal force increment are achieved as the concentration of CIPs increases. The highest magnetostriction magnitude of 0.075% is obtained with 80 wt.% of CIP, and this increment is higher than that of moderate stiffness MRE developed in the previous works. Therefore, the midrange range modulus MRE developed in this work can copiously produce the required magnetostriction value and potentially be implemented for the design of forefront sensor technology.

Microstructured Magnetoactive Elastomers for Switchable Wettability.

We demonstrate the control of wettability of non-structured and microstructured magnetoactive elastomers (MAEs) by magnetic field. The synthesized composite materials have a concentration of carbonyl iron particles of 75 wt.% (≈27 vol.%) and three different stiffnesses of the elastomer matrix. A new method of fabrication of MAE coatings on plastic substrates is presented, which allows one to enhance the response of the apparent contact angle to the magnetic field by exposing the particle-enriched side of MAEs to water. A magnetic field is not applied during crosslinking. The highest variation of the contact angle from (113 ± 1)° in zero field up to (156 ± 2)° at about 400 mT is achieved in the MAE sample with the softest matrix. Several lamellar and pillared MAE structures are fabricated by laser micromachining. The lateral dimension of surface structures is about 50 µm and the depth varies between 3 µm and 60 µm. A systematic investigation of the effects of parameters of laser processing (laser power and the number of passages of the laser beam) on the wetting behavior of these structures in the absence and presence of a magnetic field is performed. In particular, strong anisotropy of the wetting behavior of lamellar structures is observed. The results are qualitatively discussed in the framework of the Wenzel and Cassie–Baxter models. Finally, directions of further research on magnetically controlled wettability of microstructured MAE surfaces are outlined. The obtained results may be useful for the development of magnetically controlled smart surfaces for droplet-based microfluidics.

Experimental study on magnetorheological polishing fluids composition in reciprocating magnetorheological polishing

As the main factor of magnetorheological polishing (MRP), the magnetorheological polishing fluids (MRP fluids) directly affect the machining results of the workpiece surface. In this study, the preparation and performance test of MRP fluids are carried out. It is to evaluate the polishing effects of the workpiece by experimental design of the prepared MRP fluids composition, that is, the concentration of carbonyl iron particles (CIPs), the concentration of cerium oxide (CeO2), and the size of cerium oxide (CeO2) using reciprocating polishing method and establish regression equation models. Further, the optimum MRP fluids composition parameters are obtained by the optimization of regression models of the ΔRa and MRR, and the correctness of optimization results of regression models is validated by experimental verification. The results show that the ΔRa and MRR of the workpiece are affected by the MRP fluids composition parameters. The optimum MRP fluids composition parameters are found at 40 vol.% concentration of CIPs, 5 vol.% concentration of CeO2, and 7000 mesh size of CeO2. The experimental results of the ΔRa and MRR are deviated by 4.95% and 4.17% from the response results respectively by experimental verification.

Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers.

Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect of material-temperature dependence on the loss factor and phase shift angle characteristics. Two types of unageing and aging silicone-rubber-based magnetorheological elastomer (SR-MRE) with different concentrations of carbonyl iron particles (CIPs), 30 and 60 wt%, are utilized in this study. The morphological, magnetic, and rheological properties related to the loss factor and phase shift angle are characterized using a low-vacuum scanning electron microscopy, and vibrating sample magnetometer and rheometer, respectively. The morphological analysis of SR-MRE consisting of 30 wt% CIPs revealed a smoother surface area when compared to 60 wt% CIPs after thermal aging due to the improvement of CIPs dispersion in the presence of heat. Nevertheless, the rheological analysis demonstrated inimitable rheological properties due to different in-rubber structures, shear deformation condition, as well as the influence of magnetic field. No significant changes of loss factor occurred at a low CIPs concentration, whilst the loss factor increased at a higher CIPs concentration. On that basis, it has been determined that the proposed changes of the polymer chain network due to the long-term temperature exposure of different concentrations of CIPs might explain the unique rheological properties of the unaged and aged SR-MRE.

Flexible anisotropic magneto-sensitive elastomer films with out-of-plane particle chain for bionic actuator

Owing to the flexible and controllable characteristics, the magnetic composite film becomes an ideal option for future portable, efficient and multifunctional magnetic soft actuators. Here, an anisotropic magneto-sensitive elastomer film (MSEF) composite based on polydimethylsiloxane (PDMS) and high concentration of carbonyl iron particles (CIPs) was developed. The off-plane design of CIP structures endows MSEF excellent field-dependent deformability and actuation ability. The off-plane bending angle of the MSEF-30° in 87mT uniform magnetic field could reach 70.78°. Moreover, the MSEF-20° could lift a heavy object 66.4 times its own weight. The influences of particle chain orientation, CIP contents, thickness and applied magnetic field on the magneto-induced deformation behavior were fully discussed, and finite element calculations were performed to clarify the experimental results. An improved balance equation was proposed and qualitatively explained the experimental results under different magnetic fields. Based on the MSEF composite, biomimetic soft actuators with bidirectional deformation and self-sensing functions were produced respectively. The two easy preparation and programmable soft actuators could achieve the expected actuation effect, indicating that the anisotropic MSEFs have great potential as soft actuators in the fields of biomedicine, microfluidics, intelligent robots and bionics applications.

Magnetic field dependent viscoelasticity of a highly stable magnetorheological fluid under oscillatory shear

In our previous works, a new kind of magnetorheological fluid (MRF) consisting of high viscosity linear polysiloxane (HVLP) as carrier and carbonyl iron particles (CIPs) as magnetoactive dispersions, i.e., HVLP MRF, was proposed. HVLP MRF is a promising candidate in the field of heavy equipment for its long-term suspension stability. In this study, we further investigate the viscoelastic properties of HVLP MRF under oscillatory shear in order to evaluate its work performance. HVLP MRFs with different CIP concentrations (0, 20, 40, 60, and 70 wt. %) were synthesized. SEM microstructure, visible MR effect, and magnetic properties were performed. The effects of magnetic flux density, CIP concentration, shear strain, and shear angular frequency on the viscoelastic moduli were examined by using a Physica MCR-301 rheometer. The results show that the viscoelastic moduli are magnetic field dependent. The storage modulus increases with increasing the magnetic flux density, while the loss modulus presents a tendency of rising up at the beginning and declining in late. A critical particle concentration threshold (∼70 wt. %) was found to maximize the magneto-storage modulus increment. Both the upper limit of linear viscoelastic region and the flow point increase as the magnetic flux density increases. It reveals that the field dependent viscoelasticity of HVLP MRF is the result of competition between the structure-enhancement of magneto-induced particle chains and structural deformation under oscillatory shear. Additionally, in the linear viscoelastic region, HVLP MRF shows little dependence on shear angular frequency, implying an excellent working stability in a complex environment.

Sensitivities of Rheological Properties of Magnetoactive Foam for Soft Sensor Technology.

Magnetoactive (MA) foam, with its tunable mechanical properties and magnetostriction, has the potential to be used for the development of soft sensor technology. However, researchers have found that its mechanical properties and magnetostriction are morphologically dependent, thereby limiting its capabilities for dexterous manipulation. Thus, in this work, MA foam was developed with additional capabilities for controlling its magnetostriction, normal force, storage modulus, shear stress and torque by manipulating the concentration of carbonyl iron particles (CIPs) and the magnetic field with regard to morphological changes. MA foams were prepared with three weight percentages of CIPs, namely, 35 wt.%, 55 wt.% and 75 wt.%, and three different modes, namely, zero shear, constant shear and various shears. The results showed that the MA foam with 75 wt.% of CIPs enhanced the normal force sensitivity and positive magnetostriction sensitivity by up to 97% and 85%, respectively. Moreover, the sensitivities of the storage modulus, torque and shear stress were 8.97 Pa/mT, 0.021 µN/mT, and 0.0096 Pa/mT, respectively. Meanwhile, the magnetic dipolar interaction between the CIPs was capable of changing the property of MA foam from a positive to a negative magnetostriction under various shear strains with a low loss of energy. Therefore, it is believed that this kind of highly sensitive MA foam can potentially be implemented in future soft sensor systems.

Investigation on Polishing of Zirconia Ceramics Using Magnetic Compound Fluid: Relationship Between Material Removal and Surface Roughness

Zirconia ceramics have excellent applicability in the aerospace, defense, new energy, automotive, electronics, and biomedical fields. However, few investigations have been conducted on the high-precision polishing of zirconia ceramics. In this work, a polishing method using a magnetic compound fluid slurry is proposed. First, the principle and the constructed experimental setup were presented. Then, the experiments were performed that characterized the surface profile after polishing, the effect of the working gap, and the effect of the concentration of carbonyl iron particles (CIPs) on the material removal and surface quality. The results showed that the material removal ability correlated positively with the surface roughness; the smallest working gap (0.5 mm) induced greater material removal ability and better surface roughness; higher CIP concentration enabled a higher polishing force to obtain higher material removal and better surface quality. The polishing results show that surface roughness Rz of 55 nm was obtained at the surfaces of zirconia ceramics, confirming that the proposed method has the potential for polishing of zirconia ceramics.

Magnetic and Tunable Sound Absorption Properties of an In-Situ Prepared Magnetorheological Foam.

Conventional polyurethane foam has non-tunable sound absorption properties. Here, a magneto-induced foam, called magnetorheological (MR) foam, was fabricated with the feature of being able to tune sound absorption properties, primarily from the middle- to higher-frequency ranges. Three different samples of MR foams were fabricated in situ by varying the concentration of Carbonyl Iron Particles (CIPs) (0, 35, and 75 wt.%). The magnetization properties and tunable sound absorption characteristics were evaluated. From the magnetic saturation properties, the results showed very narrow and small coercivity of hysteresis loops relative to the soft magnetic properties of the CIPs. MR foam with 75 wt.% CIPs showed a higher magnetic saturation at 91.350 emu/g compared to MR foam with 35 wt.% CIPs at 63.896 emu/g. For tunable sound absorption testing, the effect of ‘shifting’ to higher frequency was also observed when the magnetic field was applied, which was ~10 Hz for MR foam with 35 wt.% CIPs and ~130 Hz for MR foam with 75 wt.% CIPs. As the latest evolution of semi-active noise control materials, the results from this study are valuable guidance for the advancement of MR-based devices.

Magneto-Rheological Fluid Assisted Abrasive Nanofinishing of β-Phase Ti-Nb-Ta-Zr Alloy: Parametric Appraisal and Corrosion Analysis.

The present work explores the potential of magneto-rheological fluid assisted abrasive finishing (MRF-AF) for obtaining precise surface topography of an in-house developed β-phase Ti-Nb-Ta-Zr (TNTZ) alloy for orthopedic applications. Investigations have been made to study the influence of the concentration of carbonyl iron particles (CIP), rotational speed (Nt), and working gap (Gp) in response to material removal (MR) and surface roughness (Ra) of the finished sample using a design of experimental technique. Further, the corrosion performance of the finished samples has also been analyzed through simulated body fluid (SBF) testing. It has been found that the selected input process parameters significantly influenced the observed MR and Ra values at 95% confidence level. Apart from this, it has been found that Gp and Nt exhibited the maximum contribution in the optimized values of the MR and Ra, respectively. Further, the corrosion analysis of the finished samples specified that the resistance against corrosion is a direct function of the surface finish. The morphological analysis of the corroded morphologies indicated that the rough sites of the implant surface have provided the nuclei for corrosion mechanics that ultimately resulted in the shredding of the appetite layer. Overall results highlighted that the MRF-AF is a potential technique for obtaining nano-scale finishing of the high-strength β-phase Ti-Nb-Ta-Zr alloy.

Effect of the components of Magnetic Compound Fluid (MCF) slurry on polishing characteristics in aspheric-surface finishing with the doughnut-shaped MCF tool

For the aspheric optical surface finished with a doughnut-shaped MCF (magnetic compound fluid) polishing tool, the performance of the polishing tool depends mainly on the properties of the MCF slurry. Therefore, understanding the effect of each MCF slurry component on the polishing characteristics is crucial to developing novel polishing techniques. In this paper, the polishing principle was depicted and the corresponding polishing jig was constructed with a six-degree-of-freedom manipulator. The conical surfaces, which were considered as special aspheric surfaces, were experimentally polished under proper polishing conditions to examine the effects of the carbonyl iron particles (CIPs) concentration and the sizes of the abrasive particles (APs) on the polishing ability to remove material/tool marks and improve work surface qualities. Theoretical analyses were also performed to gain a more comprehensive understanding of the behaviors of CIPs and APs in the magnetic field. The results were shown as follows: (1) The CIPs concentration affected positively the magnetization of the MCF slurry, leading to better performance in the removal rate of material/tool marks when a higher CIPs concentration of was applied. The best surface quality was attained with a CIPs concentration of 45 wt%. (2) Larger APs were beneficial for obtaining higher removal rates of material/tool marks. The APs with 1 μm in diameter were preferred for achieving a better surface quality. (3) Ferric clusters were formed along the magnetic line of force and their orientations changed periodically to stir the APs with the magnet revolution. (4) The Aps, at a given working gap, can squeeze the work-surface. The squeezing action was much more intense when larger APs and the MCF slurry with a higher magnetization were employed. (5) The material removal model suggested that the material was removed due to the APs and the relative motion between the work-surface and APs.

Capillary breakup extensional magnetorheometry

This work introduces a novel design of a fixture to be adapted to the commercial version of the capillary breakup extensional rheometer (CaBER), here termed as an extensional magneto-rheological fixture (ExMRFx), that allows the characterization of magnetic fluids under uniaxial extensional flow. The fixture consists of four solenoids that generate a homogeneous magnetic field with a tunable intensity on the fluid sample, while characterized in the CaBER under uniaxial extensional flow. The ExMRFx is designed in two configurations, one to impose a magnetic field parallel, while the other to impose a magnetic field perpendicular to the deformation axis. As an example of possible application, the ExMRFx has been tested with a magnetorheological fluid (MRF) consisting of a suspension of carbonyl iron particles dispersed in glycerine. The experimental results show that the filament thinning process of the MRF sample is influenced by the concentration of carbonyl iron particles used, the orientation of the magnetic field (parallel or perpendicular), the intensity of the magnetic field applied, and finally the Hencky strain imposed. Depending on the combination of these latter parameters, the MRF sample may result in a very stable filament bridging the two measuring plates, which will remain stable, as long as none of the experimental parameters change.This work introduces a novel design of a fixture to be adapted to the commercial version of the capillary breakup extensional rheometer (CaBER), here termed as an extensional magneto-rheological fixture (ExMRFx), that allows the characterization of magnetic fluids under uniaxial extensional flow. The fixture consists of four solenoids that generate a homogeneous magnetic field with a tunable intensity on the fluid sample, while characterized in the CaBER under uniaxial extensional flow. The ExMRFx is designed in two configurations, one to impose a magnetic field parallel, while the other to impose a magnetic field perpendicular to the deformation axis. As an example of possible application, the ExMRFx has been tested with a magnetorheological fluid (MRF) consisting of a suspension of carbonyl iron particles dispersed in glycerine. The experimental results show that the filament thinning process of the MRF sample is influenced by the concentration of carbonyl iron particles used, the orientation of the mag...

Parametric optimization of a newly developed magnetorheological honing process for internal finishing of EN-31 cylindrical workpieces

The magnetorheological honing process is developed to meet the industrial needs of the inner surface nano-finishing of cylindrical components with different diameters. The process utilizes the magnetorheological honing tool which constitutes four radial polarized curved permanent magnet strips. The outer surface of the MR honing tool i.e. curved permanent magnet strips has the flexibility to move radially inwards or outwards according to the requirement of the diameter of the cylindrical inner surface to be finished. In the present paper, the response surface methodology is utilized to plan and evaluate the effects of various process variables on percentage change in surface roughness (Ra) value for the finishing of EN-31 cylindrical workpieces. The EN-31 material has its extensive applications in industry for manufacturing cylindrical dies and moulds for various cylindrical plastic products. The experimental analysis concluded that the percentage change in Ra value is mostly contributed by the working gap succeeded by the MR honing tool rotational speed, the percentage concentration of SiC particles, the MR honing tool reciprocation speed and the percentage concentration of carbonyl iron particles. With the identified optimum process parameters, experimentations have been performed and least Ra value of 95 nm is obtained from the initial value of 476 nm in finishing time of 120 min. Further to observe the finishing performed by the process over the surface, the scanning electron microscopy (SEM) test is performed.

Characterization of morphological and rheological properties of rigid magnetorheological foams via in situ fabrication method

This paper presents material characteristics of a rigid magnetorheological (MR) foam that comprises polyurethane foam matrix and carbonyl iron particles (CIPs). Three different samples of MR foams are prepared by changing the concentration of CIPs (0, 35, and 70 g) in isotropic condition. In-depth characterization on the morphological properties, the field-dependent rheological behavior in terms of linear viscoelastic region and storage modulus, and the off-state sound absorption properties are then experimentally investigated. In the morphological observation, it is seen from the fluorescence micrographs that MR foam consists of open pore structure and the average size of the pores is decreased with the increment in CIPs content. In the rheological test of MR foam, it is identified that MR foam with the addition of 70 g of CIPs to the total of polyol and isocyanates (100 g) can enhance the storage modulus up to 112% compared with MR foam without CIPs. In the meantime, from the acoustic absorption test, it is shown that the maximum peaks of sound absorption coefficient (SAC) are shifted to the low frequency and the SAC is increased up to 229% due to the decrement in the pores size and increment in the storage modulus. The results achieved from this material characterization of MR foam provide useful guidelines for the development of new type smart materials associated with MR fluids and for the findings of appropriate applications which require controllability of both the stiffness and acoustic properties.

Monitoring sedimentation of magnetorheological fluids using a vertical axis monitoring system with a low aspect ratio sensor coil**This research was conducted at the University of Maryland while the first author was a visiting student.

Adaptive energy absorbers (EAs) utilizing magnetorheological fluids (MRFs) are currently being investigated for severe impact or shock mitigation problems because magnetorheological energy absorbers can adjust stroking load to account for severity of impact and payload mass. Utilizing MRFs in such EAs requires a highly stable suspension that maintains a uniform concentration. Suspension stability of MRFs can be studied using a MRF column and an automated vertical axis inductance monitoring system (AVAIMS), where an inductance sensor is translated up and down the vertical MRF column to track the mud-line, defined as the boundary between the clarified fluid at the top of the column and the MRF below. The rate of descent of the mud-line is typically referred to as the sedimentation rate of the MRF. In this paper, a refined inductance sensor is developed that features a low aspect ratio coil to better localize rapid changes in concentration or sedimentation zone boundaries, as well as to improve symmetry of the applied magnetic field in the MRF sample enclosed by the sensor. This low aspect ratio solenoid (LARS) sensor was developed to measure the vertical distribution of the concentration of carbonyl iron particles in the MRF column. Compared with the high aspect ratio solenoid sensor used in our prior work, the results of FEM simulation and sedimentation experiments demonstrate that the LARS sensor was better able to localize rapid changes in concentration or density. Using the AVAIMS with the refined LARS sensor, a method was developed, based on the measured concentration gradient profile, to identify sedimentation zone boundaries in an MRF column, and these results were compared to our prior work using the measured concentration profile only. Sedimentation zone boundaries that are consistent with Kynch’s sedimentation theory were obtained using the concentration gradient profile method, such as monotonically descending mud-line, linearly ascending gel-line, and linearly ascending cake-line. Key metrics to characterize the time histories of the sedimentation zone boundaries are measured including mud-line descent rate, gel-line ascent rate, and cake-line ascent rate. Identification of sedimentation zone boundaries using the LARS sensor in conjunction with the concentration gradient profile method exhibited two main advantages including the direct measurement and improved localization of the large concentration change that occurs at a sedimentation zone boundary, and the elimination of sensor bias.

Magnetic circuit analysis to obtain the magnetic permeability of magnetorheological elastomers

The magnetic permeability of magnetorheological elastomers must be known for their long-term use in the actual engineering systems. In this article, the magnetic permeability of both isotropic and anisotropic magnetorheological elastomers has been determined using a new method. The magnetic induction was measured and a closed magnetic circuit analysis was carried out to obtain the magnetic permeability of magnetorheological elastomers for both isotropic and anisotropic magnetorheological elastomers with 10%–50% volume concentration of carbonyl iron particles. The magnetic permeability was increased with increasing particle concentration for both isotropic and anisotropic magnetorheological elastomers as we could expect. The isotropic permeability is always lower than the anisotropic permeability. The maximum relative permeability value of 6.6 was obtained for 50% particle volume concentration. The experimental results also show a good agreement with theoretical predictions and previous investigations.

Atomic-level finishing of aluminum alloy by chemo-mechanical magneto-rheological finishing (CMMRF) for optical applications

Nanofinished aluminum alloys are widely used in optics as metallic mirrors, micro-electronics and micro-mechanical assemblies. In general, the ductile materials like aluminum and copper are being machined by diamond turn machining (DTM) process to get the nanometric surface finish. However, it is impossible to achieve an atomic level surface finish by conventional random finishing processes like lapping. With a newly developed chemo mechanical magnetorheological finishing (CMMRF) process, an experimental investigation has been carried out on Al-alloy by implementing suitable chemical reactions on the superficial layer of the workpiece. A full experimental design has been performed to optimize the process by varying several parameters such as concentration of chemicals, concentration of abrasives, concentration of carbonyl iron particles and working gap. Effect of different parameters has been studied an average surface roughness value (Ra) of less than 2 nm was achieved, which was further improved by optimizing the process parameters. The best result of CMMRF finished aluminum (0.597 nm) was way better than DTM and chemo-mechanical polishing process. In terms of reflectance, in the range of 300–2200 nm the processed surface was found to have 5% higher value in comparison with sputtered counterpart. Also, it was observed that finishing of aluminum caused its surface to shift from hydrophilic to hydrophobic and then to the super-hydrophilic region with a contact angle of 16°. By this experimentation, more than 98% improvement on surface finish has been observed. Therefore, it has been concluded that the CMMRF process can finish aluminum alloy of the order of few angstrom (Å).

Polishing characteristics and mechanism in magnetorheological planarization using a permanent magnetic yoke with translational movement

Translational movement was integrated into a magnetorheological planarization process that uses a permanent magnet yoke with a straight air gap as magnetic source in order to improve surface planarity. The effects of the process conditions, including stroke and velocity of the translational movement, work and excitation gaps and concentration of carbonyl iron particles, on the polishing forces, surface roughness and volumetric removal rate were systematically investigated. The results showed that translational movement had insignificant effect on the polished surface finish, but considerably improved the surface planarity. The surface quality and volumetric removal rate were found to be affected by carbonyl iron particles concentration, and work and excitation gaps. Based on the parametric study, theoretical and empirical models were established for predicting the polishing forces, surface roughness and volumetric removal rate in this magnetorheological process.