SiC Reinforcement Research Articles

Study on the vibration and density properties of hybrid MMC with reinforcement of SiC and flyash

The current research work contains the study of density properties and the vibration analysis of LM22 with Silicon carbide and flyash reinforcement to form a metal matrix composite (MMC) and is compared with the parent material. LM22 is majorly used in the automobile industry as it is easy to cast, machine as well as to weld. The LM22 metal matrix Composites with 3–5 percent of reinforcement is found to have greater density than the base material. The post annealing damping ratio obtained is lesser than the base material however, it was observed that by increasing the reinforcement percentage it increased by 0.5%.

Experimental Investigation of Process Parameters of Al-SiC-B4C MMCs Finished by a Novel Magnetic Abrasive Flow Machining Setup

Abrasive flow machining (AFM) is one of the non-conventional finishing processes used to attain good surface quality and high material removal. However, limited attempts have been made to improve the performance of these processes. This paper presents a novel magnetic abrasive flow machining (MAFM) setup fabricated by adding a magnetization effect in which a nylon fixture and permanent magnets are replaced by a newly fabricated aluminium fixture and coil-type magnets, respectively. Inner cylindrical surfaces of hybrid Al/SiC/B4C metal matrix composites (MMCs) are finished by the MAFM process. One variable at a time (OVAT) approach is used for studying the effect of 6 input parameters, extrusion pressure (Ep), the number of cycles (N), abrasives concentration (C), workpiece material (Wp), abrasive mesh size (M), and magnetic flux density (Mf) upon response parameters, material removal rate (MRR) and change in surface roughness (ΔRa). The experimental results obtained for MRR and ΔRa show a significant improvement from 3.92 to 7.68 μg/s and 0.49 to 0.74 μm, respectively due to the increase of the extrusion pressure from 1 to 9 Mpa. The MRR and ΔRa was reduced from 6.89 to 6.78 μg/s and 0.46 to 0.22 μm, respectively with an increase in mesh number of abrasives from 80 to 400. The variation in concentration of abrasives from 40 to 60 % shows an improvement in MRR from 4.51 to 6.42 μg/s; whereas, there is a negligible effect on ΔRa which comes out from 3.82 to 3.86 μm. The MMCs, which are used for the experimentation shows a decline in MRR and ΔRa from 5.12 to 3.85 μg/s and 0.77 to 0.42 μm, respectively. This happened because there was a percentage change of reinforcement of SiC from 9 to 7 % and B4C from 1 to 3 % in Al-6063. An increase in the number of cycles from 50 to 250 shows a significant improvement in both MRR and ΔRa from 1.79 to 3.75 μg/s and 0.97 to 1.86 μm, respectively. Variation in magnetic effect also significantly improves MRR and ΔRa from 1.35 to 3.17 μg/s and 0.38 to 1.06 μm, respectively, when it is varied from 0.15 - 0.45 Tesla. The work carried out shows an overall significant improvement in MRR and ΔRa by using the MAFM process. The MAFM process finds a wide range of applications in finishing like surgical instruments, mechanical components, aerospace industry, electronics industry, etc. HIGHLIGHTS The hybrid MMCs (Al/SiC/B4C) are finished by novel MAFM setup An aluminium fixture and coil-type magnets play a significant role for finishing the workpiece surfaces An abrasive laden media acts as a cutting tool in the finishing process The OVAT approach is used for investigating the parametric effect The extrusion pressure, number of cycles and magnetic flux density are the significant parameters affecting the MRR and ΔRa GRAPHICAL ABSTRACT

Mechanical, wear and corrosion behaviors of AZ91/SiC composite layer fabricated by friction stir vibration processing

In this work, the effect of vibration on the mechanical, corrosion and wear characteristics of AZ91 composite layers fabricated by a modified friction stir processing has been examined. The vibration was implemented by the motor into the fixture placed beneath the work-piece. It was observed that vibration could highly modify the microstructure and mechanical properties of the composite layer owing to the increase in strain rate, deformation, and expansion of the material flow zone. Tensile strength increased from around 203 MPa for the samples processed by friction stir process (FSP) to about 234 MPa for the samples processed by friction stir vibration process (FSVP). Furthermore, a more uniform distribution of reinforcement SiC particles with less agglomerated domains was achieved using FSVP. The FSVPed sample exhibited better wear resistance compared to the conventional FSPed sample and the base metal. In this study, the principal common wear mechanisms were delamination, oxidation, abrasion, and plastic deformation. It was also found out that both FSPed and FSVPed specimens experienced lower hydrogen evolution volume during the immersion time compared to the base metal. Finally, the corrosion resistance of FSVPed sample highly increased compared to the FSP and base metal.

Influence of SiC on solid particle erosion and mechanical behaviour of Al–25Zn alloy based novel metal matrix composites fabricated through stir casting technique

ABSTRACT This investigation studied the influence of SiC reinforcement (0, 10, 15 and 20 wt.%) on solid particle erosion and mechanical behaviour of novel Al–25Zn alloy metal matrix composites fabricated by the stir casting technique. The erosion wear experiments were conducted following the ASTM G-76 standard for various impact velocity, impingement angle, and erodent temperature as per Taguchi L16 orthogonal array using air jet erosion test rig with erodent silica sand particles of irregular shapes with size approximately 150 µm. The attempt has been made to establish linear and nonlinear correlations between input parameters and erosion rates. The artificial neural network and the Taguchi approach were used to identify the optimal parameter combination for the minimum erosion rate. The results show a significant alteration in properties with reinforcement of SiC content. The analysis of variance, signal to noise ratio, and morphology of eroded surfaces indicates that impact velocity is the most dominating parameter for the erosion rate among studied parameters. The erosion rate increased with the rise in impact velocity, whereas the highest erosion rate is observed with 30° impingement angle. For identical test conditions, optimum mechanical and erosion characteristics are noticed for the composite with 15% SiC.

Effect of Sintering Mechanisms on the Mechanical Behaviour of SiC and Kaoline Reinforced Hybrid Aluminium Metal Matrix Composite Fabricated through Powder Metallurgy Technique

Present work focusses on the fabrication of Al-10% SiC-4% Kaoline HMMC by using conventional sintering, Microwave- assisted sintering (MAS) and Spark Plasma Sintering (SPS) techniques. Tensile, Compression and hardness tests were performed as per ASTM standards to study the effect of sintering mechanisms on the fabricated HMMC specimens. Results reveal that an enhancement of 13.3% in U.T.S and 11.7% Compression strength was observed in the Spark Plasma Sintered HMMC when compared to conventional sintered composite specimens because of lesser sintering temperature, time and the absence of intermetallic compounds in the Spark Plasma Sintering process. The formation of the Al2Cu intermetallic compound was identified in the XRD pattern of conventionally sintered Al-10% SiC-4% Kaoline HMMC sample due to the high sintering time and temperature which leads to inadequate mechanical properties. The fractured surface of tensile specimens reveals the presence of cleavages on the conventionally sintered HMMC which confirms the brittle fracture, and the existence of dimples on the Microwave sintered and Spark Plasma Sintered samples which signify that the ductile mode of failure in HMMC samples. Out of the three sintering techniques, Spark Plasma Sintering exhibits superior mechanical properties and lesser porosity levels.

Optimization of process parameters inend milling of Al-4032 based metal matrix composite using TGRA

ABSTRACT The Al-4032/SiC metal matrix composites are quite useful for low density, high corrosion resistance and improved mechanical properties. Usually, 2–8% SiC reinforcement has been researched for various industrial applications. Progressive increase in the reinforcement (SiC) composition in the Al-4032 matrix causes reduction in ductility and increase in brittleness. This paper presents the research on machining aspects of the Al-4032 with 3% SiC reinforcement. Work has been carried out to study the response of cutting speed (CS), feed rate (FR) and depth of cut (DOC) upon the material removal rate (MRR) and surface roughness (SR). The experiments have been done on the Computer Numeric Control (CNC) vertical machine centre. The machining (end milling) experiments have been conducted following the Taguchi’s L9 orthogonal array. For attempting the bi-objective optimisation (i.e. maximisation of MRR and minimisation of the surface roughness), Taguchi’s grey relational analysis (TGRA) has been implemented using equal weightage to both the response parameters (W1 = W2 = 0.5). The model so obtained has been tested through ANOVA to discover the statistically significant elements. The CS (52.40%) appears to make the largest percentage contribution to the composite response, followed by the FR (26.60%), and the DOC (19.45%).

Microstructural characterization of TiB2–SiC–BN ceramics prepared by hot pressing

This research intended to evaluate the discrete and cumulative impacts of hexagonal SiC and BN additives on the microstructural features and consolidation behavior of TiB2-based materials. All specimens were sintered at the same hot-pressing conditions at 2000 °C under 50 MPa for 120 min. Both discrete and synergetic influences of SiC and hBN ingredients on the sintering behavior of TiB2 were noticeable so that three near fully dense ceramics were secured. Due to a chemical interaction between SiC and TiO2 phases, in-situ SiO2 was generated during the hot pressing of the TiB2–SiC sample. Although no in-situ phase could be detected in the composite introduced by hBN additive, the X-ray diffraction pattern and electron microscopy images uncovered the in-situ generation of the TiC phase in the ternary and binary systems of TiB2–SiC-hBN and TiB2–SiC. While both TiB2–SiC-hBN and TiB2–SiC samples were mostly fractured intergranularly, a mixed transgranular-intergranular fracture mode was seen in the fracture surface of the TiB2-hBN ceramic. The finest microstructure was attained when both SiC and hBN additives were incorporated into the TiB2 matrix at the same time. Finally, the sample introduced by 25 vol% SiC reinforcement reached the most significant Vickers hardness (24.3 GPa), while the TiB2–SiC-hBN composite offered the highest fracture toughness (6.7 MPa m1/2).

Mechanical and Electrical Properties of Nano Al-Matrix Composites Reinforced with SiC and Prepared by Powder Metallurgy

Nano Al-matrix composites reinforced with SiC were prepared by powder metallurgy process. The percentages of added SiC were varied between 0, 2, 4, 6, and 8 wt. %. The starting powders were milled in high-energy ball mill for 10hrs to convert into nanopowders; then compacted and sintered for 1h in an argon atmosphere at 400, 500, and 570°C. X-ray technique and transmission electron-microscope were utilized to examine the prepared powders, while scanning electron-microscope was utilized to test the sintered composites. The relative density, apparent porosity, electrical conductivity, and mechanical properties (microhardness, elastic moduli, and compressive strength) of sintered composites were studied. The results showed no sign for phase changes after milling, and the SiC reinforcement was uniformly distributed in the matrix. The relative density and electrical conductivity were decreased with increasing SiC content, while the apparent porosity was increased. It is also found that the mechanical properties were improved with increasing SiC content. Also, all properties were improved with increasing sintering temperature. The hardness, compressive strength, bulk modulus of Al-8wt.% SiC composite sintered at 570°C were 885.4 MPa, 276.2 MPa, and 135.9 GPa, respectively.

Development of high-performance aluminium 6061/SiC nanocomposites by ultrasonic aided rheo-squeeze casting method

In the modern era, the need for new products with novel processing and multipurpose materials is increased. The current market requirements for engineering applications are lightweight, high strength and low-cost materials. This paper explores the novel development process of high-performance nano cermet material for aerospace applications. Herein, lightweight aluminium 6061 + 2% of SiC (40 nm) nano cermet was fabricated through the casting method. The effects of ultrasonication, double stir casting or rheocasting, and squeezing pressure on nano cermet fabrication were successfully investigated by comparing their physical, thermal and mechanical properties. Scanning electron microscopy was employed to analyse the morphology of the cermets, and the presence of reinforcements was verified through EDS. The reinforcement of SiC into Al 6061 improved density, hardness, and reduction in porosity and grain refinement. This study reveals a novel fabrication process of ultrasonic-aided rheo-squeeze casting technique which enhanced the mechanical properties of the cermets compared to Al 6061 alloy due to nanoparticles homogeneous distribution, nominal agglomeration and porosity.

Mechanical and Microstructural Characterization of Friction Stir Welded SiC and B4C Reinforced Aluminium Alloy AA6061 Metal Matrix Composites.

This study focuses on the properties and process parameters dictating behavioural aspects of friction stir welded Aluminium Alloy AA6061 metal matrix composites reinforced with varying percentages of SiC and B4C. The joint properties in terms of mechanical strength, microstructural integrity and quality were examined. The weld reveals grain refinement and uniform distribution of reinforced particles in the joint region leading to improved strength compared to other joints of varying base material compositions. The tensile properties of the friction stir welded Al-MMCs improved after reinforcement with SiC and B4C. The maximum ultimate tensile stress was around 172.8 ± 1.9 MPa for composite with 10% SiC and 3% B4C reinforcement. The percentage elongation decreased as the percentage of SiC decreases and B4C increases. The hardness of the Al-MMCs improved considerably by adding reinforcement and subsequent thermal action during the FSW process, indicating an optimal increase as it eliminates brittleness. It was seen that higher SiC content contributes to higher strength, improved wear properties and hardness. The wear rate was as high as 12 ± 0.9 g/s for 10% SiC reinforcement and 30 N load. The wear rate reduced for lower values of load and increased with B4C reinforcement. The microstructural examination at the joints reveals the flow of plasticized metal from advancing to the retreating side. The formation of onion rings in the weld zone was due to the cylindrical FSW rotating tool material impression during the stirring action. Alterations in chemical properties are negligible, thereby retaining the original characteristics of the materials post welding. No major cracks or pores were observed during the non-destructive testing process that established good quality of the weld. The results are indicated improvement in mechanical and microstructural properties of the weld.

Mechanical, Physical and Thermal Behaviour of SiC and MgO Reinforced Aluminium Based Composite Material

Mechanical, Physical and Thermal Behaviour of SiC and MgO Reinforced Aluminium Based Composite Material

Microstructural Characterization and Mechanical Behaviour of SiC and Kaoline Reinforced Aluminium Metal Matrix Composites Fabricated Through Powder Metallurgy Technique

Aluminium metal matrix composites are widely used in the automobile industry due to their superior properties like high strength to weight ratio, high ductility and better corrosion resistance. In this study, the effect of naturally available and low-cost kaoline particles on the microstructural and mechanical behaviour of Al- SiC- Kaoline Hybrid metal matrix composite was investigated. Al-10 % SiC- X% Kaoline (X = 0, 2, 4, 6, 8) composite samples were fabricated through powder metallurgy technique by applying a compaction pressure of 350 MPa. The fabricated composite samples were subjected to Density, Hardness, Tensile and impact tests to study the mechanical behaviour of fabricated hybrid composite. The presence of SiC and Kaoline reinforcements was confirmed by using SEM and X-Ray Diffraction analysis. It was observed that the maximum ultimate tensile strength ( U.T.S ) and maximum Yield Strength ( Y.S) of the hybrid composite were found to be 263 MPa and 202 MPa for Al-10 %SiC-4 %kaoline reinforcement. The formation of the intermetallic compound such as Al2Cu was observed in XRD and SEM analysis for Al-10 % SiC-6 % kaoline and Al-10 % SiC-8 % of kaoline reinforcement which leads to decrease in the U.T.S and Y.S of fabricated specimens. The impact strength of Al-10 %SiC-8 % kaoline found to be decreased by 44.4 % compared to unreinforced Aluminium due to the presence of harder SiC and Kaoline reinforcements particles. To study the fracture mechanism, Scanning Electron Microscopy study was carried on the fractured tensile specimens which reveal that ductile fracture in unreinforced Al, Al-10 % SiC, Al-10 % SiC-2 % Kaoline due to the formation of dimples and brittle fracture was observed in Al-10 % SiC-4 % Kaoline, Al-10 % SiC-6 % Kaoline and Al-10 % SiC-8 % Kaoline due to the existence of cleavages and microcracks. The best suitable combination of mechanical properties was obtained at Al-10 % SiC-4 % Kaoline hybrid composite.

SiC honeycomb reinforced Al matrix composite with improved tribological performance

SiC honeycomb ceramic reinforced Al (SiCH/Al) composite with anisotropic microstructure was fabricated by spontaneous infiltration method, and the effect of SiC honeycomb reinforcement on the tribological performance of SiCH/Al composite in axial and radial directions was investigated. The SiC particle reinforced Al (SiCP/Al) composite with the same SiC content was prepared as a counterpart to reveal the effect of SiC reinforcement architecture on the tribological performance of the Al-matrix composites. Compared with the SiCH/Al composite in radial direction and the SiCP/Al composite, the SiCH/Al composite in axial direction shows the highest thermal conductivity of 140.96 W m−1 K−1 and hardness of 97.14 H V, which hinder the formation of oxidative wear and eroding of counter ball. Additionally, a mechanical mixed layer can be formed on the worn surface of SiCH/Al composite in axial direction during the friction process. As a consequence, the SiCH/Al composite in axial direction exhibits the optimal tribological performance with the lowest averaged friction coefficient (0.53) and wear rate (0.98 mm3 N−1 m−1). The results indicate that the SiC honeycomb reinforcement is a promising candidate to improve the tribological performance of metal-matrix composites, especially in their axial direction.

Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

HfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

Numerical Analysis of Particulate Migration Behavior within Molten Pool during TIG-Assisted Droplet Deposition Manufacturing of SiC Particle-Reinforced Aluminum Matrix Composites.

A transient three-dimensional (3D) numerical model was established to illustrate the heat transfer, fluid flow and particle migration behaviors in the molten pool during TIG-assisted droplet deposition manufacturing (DDM) of SiC particle-reinforced aluminum matrix composites (AMCs). The effect of temperature-dependent physical properties and the interaction between the SiC reinforcement and the liquid metal matrix were considered. A double-ellipsoidal volumetric heat source model was adopted to simulate the energy interactions between the pulse square-wave variable polarity TIG welding arc and the moving substrate. Free surface fluctuations of molten pool due to arc force and sequential droplet impact are calculated with volume of fluid (VOF) method in a fixed Eulerian structured mesh. The numerical model, capable of capturing the impact, simultaneous spread, and phase change of the droplets as well as the motion trajectory and terminate distribution state of the reinforcement particles, is key tool to understand the formation mechanism of the TIG-assisted DDM of SiC particle-reinforced AMCs. The numerical model was validated by the metallographic observations, and the calculated particle distribution and solidification morphology of deposited layer agree well with the experimental measurements.

Finding the optimum concentration of silicon carbide and graphite particles on the tensile strength, hardness and wear properties of aluminium matrix composites by RSM approach

The present investigation aims to determine the optimum concentration of SiC and graphite reinforcements in AA7075 matrix based hybrid composites to obtain better tensile strength, hardness, coefficient of friction and wear rate using RSM. Reinforcement particles of SiC varied from 5% to 15% whereas graphite particles varied from 3% to 7% in the AA7075 matrix. A central composite design of RSM was adopted to develop the numerical model, and the statistical data were derived using analysis variances to evaluate adequacy of the model. Meanwhile, the conformity test has been conducted to validate the developed numerical model. Following this, the output responses of the optimized conditions were taken into account for the characterization of microstructure, fractured surface, and worn surface characters using optical microscope, and scanning electron microscope. The effect of SiC and graphite particles on the tensile strength, hardness, and wear properties and its result were reported in detail along with comparison of previous researchers.

Effect of hybrid reinforcement on microstructure and mechanical properties of AZ61 magnesium alloy processed by stir casting method

In this present study, AZ61 magnesium alloys reinforced with a low weight fraction of alumina (Al2O3: 2 wt %) and silicon carbide (SiC: 0.5, 1, 1.5 wt %) nanoparticle hybrid composites were fabricated using the gravitating mechanical stir casting (GMSC) method. The microstructure analysis reveal a monolithic alloy structure composed of α-Mg grains with intermetallic secondary (β-Mg17Al12) phases uniformly distributed at the grain boundaries. The addition of reinforcements to the monolithic alloy reduces their mean size and leads to a breaking down of the β-Mg17Al12 phases from round to needle like in shape. The hardness, tensile and compressive strength results show a direct relationship with the SiC reinforcement contents, the maximum values obtained the addition being 1 wt% SiC along with AZ61+2 wt%Al2O3 hybrid composite.

The effect of SiC content in aluminum-based metal matrix composites on the microstructure and mechanical properties of welded joints

Aluminum metal matrix composites of the varying percentage of SiC reinforcement were welded using the tungsten inert gas welding technique. For all the conditions of the specimen, the welding parameters were kept identical. The welded composites were thermally aged to peak age-hardening conditions. Significant differences in microstructure exist between aged and non-age hardened composites in terms of misorientation, grain boundary fractions and stored energy. These differences in microstructure were seen through identical changes in the mechanical behavior of the welded composites. After aging, microstructure showed refinement in grain size and preferential orientation. Hardness and tensile strength increased at different rates with increase in SiC content indicating that hardness was a clear function of stored energy and strength had a dependence on the misorientation. EBSD measured suggests that due to age hardening, a rearrangement in dislocation substructures occurred with precipitation of Mg2Si or increasing SiC content followed by dynamic recovery of the weld metal region which leads to enhancement of hardness. The increase in tensile strength with decreased misorientation was a clear indication that the effect of annihilation of dislocations as a result of recovery was less pronounced and precipitation strengthening was dominant. The present study aims to address the role of SiC addition in aluminum metal matrix composites on the welded microstructure and finally relating the microstructural changes to the observed mechanical behavior of the welded joints. The study reveals that strength not only depends on the average value of misorientation but also on the distribution of misorientation in the microstructure.

A new approach of abrasive wear performance of flame sprayed NiCrSiBFeC/SiC composite coating

The abrasive wear resistance of coatings of NiCrBSiFeC with the addition of 40% SiC applied by the flame spray process was evaluated. 420 μm thick layers were applied onto AISI 1020 steel substrates. The powder used is a commercial Metco ML16-C (Ni16Cr4Si4B3Cu3Mo2.5Fe0.5C) with particle size in the range of −125 + 53 μm and mechanically mixed for 2 h with medium-sized 29 μm SiC powder. The coatings were further remelted by the technique of surface flame melting. The surface and cross-sectional characterization, before and after the remelting, was performed by scanning electron microscopy (SEM), dispersive energy microanalysis (EDS), and x-ray diffraction (XRD). Microhardness profiles (HV0.05) were obtained in the cross-section. Abrasion tests were performed according to the ASTM G65 standard. It was found that the remelting process decreased the porosity, eliminated the defects of the interlayer as well as coating/substrate interfaces. The addition of the 40% SiC reinforcement caused an increase in the microhardness values mainly in the regions closer to the surface, on average 1119 HV0.05 in coatings without remelting and 1086 HV0.05 after remelting. The remelting decreased the mass loss, being 8.4 times less in the coatings without adding SiC and 6.8 times less in the coatings reinforced with SiC. NiCrBSi coatings reinforced with SiC and not remelted showed 17% less loss of mass. The quantitative analysis carried out by XRD enables us to confirm that the abrasive wear mainly causes significant loss of the eutectic phases (Ni3Si2 and Ni3B) and the detachment of the Cr carbides and borides. Further, the austenitic matrix (Ni γ) shows superior resistance to wear.

Comparison of tool wear during friction stir welding of Al alloy and Al-SiC metal matrix composite

Aluminum matrix composites have received considerable attention due to their high specific strength and specific stiffness, high hardness, and wear resistance along with being light in weight. These composites are preferably joined using friction stir welding process. The major concern in friction stir welding is the wear of the welding tool pin which is the backbone of the process. The wear is due to the prolonged contact between the tool and the harder reinforcements in the composite materials. The present work deals with the study of tool wear and its surface roughness with respect to different selected friction stir welding parameters such as rotational speed, transverse speed, length of weld, and different composition of Aluminum composite. It was found that the total amount of material removed from the tool and the surface roughness of the tool is in direct proportion to the rotational speed of the tool and the length of the weld but inversely proportional to the transverse rate. The increase in wt.% of SiC reinforcement leads to the higher tool wear but reduces the surface roughness of the tool.