Stephen F. Corbin

A study of transient liquid-phase bonding of Ag-Cu using differential scanning calorimetry

A novel approach using differential scanning calorimetry (DSC) to quantify interface kinetics in a solid/liquid diffusion couple is applied to characterize the isothermal solidification stage during transient liquid-phase (TLP) bonding of Ag and Cu using a Ag-Cu interlayer. When the DSC results are properly interpreted, the measured interface kinetics are more accurate than those obtained using traditional metallographic techniques. Experimental results are compared to predictions for isothermal solidification given by a selection of analytical models. The comparison yields close agreement with a solution that assumes a moving boundary; but accuracy of the predictions is very sensitive to selection of solute diffusivity. Metallographic inspection of the DSC samples and traditional TLP bonds validates the kinetics measured using this technique, and supports the prediction given by the analytical model. This study shows that the method of using DSC to quantify interface kinetics is valuable in the refinement of process parameters for TLP bonding. Furthermore, simple analytical solutions can be applied to predict the process kinetics of isothermal solidification in simple binary systems with considerable accuracy when the effects of grain boundaries can be neglected, thus reducing the need for complex numerical models when developing process parameters.

An Experimental Study of Transient Liquid Phase Bonding of the Ternary Ag-Au-Cu System Using Differential Scanning Calorimetry

An experimental approach using differential scanning calorimetry (DSC) has been applied to quantify the solid/liquid interface kinetics during the isothermal solidification stage of transient liquid phase (TLP) bonding in an Ag-Au-Cu ternary alloy solid/liquid diffusion couple. Eutectic Ag-Au-Cu foil interlayers were coupled with pure Ag base metal to study the effects of two solutes on interface motion. Experimental effects involving baseline shift and primary solidification contribute to a systematic underestimation of the fraction of liquid remaining. A temperature program has been used to quantify and correct these effects. The experimental results show a linear relationship between the interface position and the square root of the isothermal hold time. The shifting tie line composition at the interface has been shown to affect the DSC results; however, the impact on the calculated interface kinetics has been shown to be minimal in this case. This work has increased the knowledge of isothermal solidification in ternary alloy systems and developed accurate experimental methods to characterize these processes, which is valuable for designing TLP bonding schedules.

Study on laser parameters effect on morphology of in-situ Fe-TiC particles deposition on mild steel using laser cladding process

Over the last decade, researchers have demonstrated interest in tribology and prototyping by the laser cladding process. In-situ laser cladding enables the formation of a uniform clad by melting the powder to form desired composition from pure powder components. Since TiC has desirable properties, such as hardness, wear and corrosion resistance, Ti and Graphite (C) are used as a composite material (i.e., TiC) to increase hardness and wear resistance of AISI 1030 carbon steel.In previous papers, the effect of laser parameters on the clad quality was investigated. In this paper two combined parameters (i.e. the effective energy per unit area (Eeff) and the powder deposition density (PDD) were plotted in order to recognize the high quality clad zone. Afterward a range of clad conditions with constant and variable effective energies in high quality clad zone were conducted to study the role of the effective energy on morphology and distribution of TiC particles.Complete metallurgical bonding between substrate and the clad was observed in all samples.SEM analysis has been used to study the TiC particles’ morphology from the bottom to the top of the clad. Presence of in situ TiC particles in Fe (Ti) solid solution has been confirmed by XRD and EDS analysis.Over the last decade, researchers have demonstrated interest in tribology and prototyping by the laser cladding process. In-situ laser cladding enables the formation of a uniform clad by melting the powder to form desired composition from pure powder components. Since TiC has desirable properties, such as hardness, wear and corrosion resistance, Ti and Graphite (C) are used as a composite material (i.e., TiC) to increase hardness and wear resistance of AISI 1030 carbon steel.In previous papers, the effect of laser parameters on the clad quality was investigated. In this paper two combined parameters (i.e. the effective energy per unit area (Eeff) and the powder deposition density (PDD) were plotted in order to recognize the high quality clad zone. Afterward a range of clad conditions with constant and variable effective energies in high quality clad zone were conducted to study the role of the effective energy on morphology and distribution of TiC particles.Complete metallurgical bonding between substrate...

Correlation between temperature distribution and formed microstructure of in-situ laser cladding of Fe-TiC on carbon steel

One of the unique aspects of in-situ laser cladding is to create a uniform clad by melting the powder and a thin layer of the substrate to form a composite of pure powder components with minimal dilution. Therefore, this technique can be an excellent candidate for hardfacing process by deposition of multiple clad beads side by side on a low cost base material. Since TiC has desirable properties such as hardness, wear and corrosion resistance, in this work, the hardfacing process of AISI 1030 carbon steel using titanium (Ti) and graphite (C) as a composite coating material (i.e., Fe(Ti)-TiC) is investigated using a numerical and experimental analysis. In order to study the microstructure of the TiC morphology and distribution in the clad, a 3D time-dependent numerical model and ternary phase diagram are used to interpret the experimental results along with the temperature distributions formed throughout the deposition process. The morphology and distribution of TiC particles are studied by means of SEM, XRD.One of the unique aspects of in-situ laser cladding is to create a uniform clad by melting the powder and a thin layer of the substrate to form a composite of pure powder components with minimal dilution. Therefore, this technique can be an excellent candidate for hardfacing process by deposition of multiple clad beads side by side on a low cost base material. Since TiC has desirable properties such as hardness, wear and corrosion resistance, in this work, the hardfacing process of AISI 1030 carbon steel using titanium (Ti) and graphite (C) as a composite coating material (i.e., Fe(Ti)-TiC) is investigated using a numerical and experimental analysis. In order to study the microstructure of the TiC morphology and distribution in the clad, a 3D time-dependent numerical model and ternary phase diagram are used to interpret the experimental results along with the temperature distributions formed throughout the deposition process. The morphology and distribution of TiC particles are studied by means of SEM, XRD.

Thermal control managing for in-situ synthesis of Ti-C-Fe system by laser cladding on carbon steel

In-situ laser cladding enables the formation of a uniform clad by melting the powder and substrate to form a composition from pure powder components. Since TiC has desirable properties such as hardness, wear and corrosion resistance, titanium (Ti) and graphite (C) are used as a composite material (i.e., TiC) to increase hardness and wear resistance of AISI 1030 carbon steel. To increase the corrosion, erosion, and wear resistance of a low grade material substrate the entire substrate surface must be coated by the multi-track cladding. Preliminary experiments indicate that deposition of multi-track of TiC-Fe base composite results in different TiC morphologies which might affect the clad properties. In this paper, effect of different heat input on TiC morphology has been studied.Results show that different heat input which are designed by laser parameters affect the TiC morphology. SEM and EDS data show that TiC particles are built up uniformly during the laser cladding process in the iron matrix with dissimilar morphologies.In-situ laser cladding enables the formation of a uniform clad by melting the powder and substrate to form a composition from pure powder components. Since TiC has desirable properties such as hardness, wear and corrosion resistance, titanium (Ti) and graphite (C) are used as a composite material (i.e., TiC) to increase hardness and wear resistance of AISI 1030 carbon steel. To increase the corrosion, erosion, and wear resistance of a low grade material substrate the entire substrate surface must be coated by the multi-track cladding. Preliminary experiments indicate that deposition of multi-track of TiC-Fe base composite results in different TiC morphologies which might affect the clad properties. In this paper, effect of different heat input on TiC morphology has been studied.Results show that different heat input which are designed by laser parameters affect the TiC morphology. SEM and EDS data show that TiC particles are built up uniformly during the laser cladding process in the iron matrix with diss...

Analysis of aluminium brazing sheet differential scanning calorimetry data

Differential scanning calorimetry (DSC) measurements have provided insight into metallurgical reactions which can occur during joining of Al brazing sheet. Researchers have claimed that DSC is sensitive enough to differentiate between brazing sheets with different initial conditions; however, no rigorous proof of this claim has been given. The sensitivity of DSC measurements, as measured by changes in melting peak area, to experimental factors such as DSC sample preparation, sample orientation during testing and starting sheet temper has been investigated. A 23 factorial design was used, and the results were analysed using analysis of variance. The results showed that only the sheet punching direction during sample preparation had a statistically significant influence on the DSC measurements. Microstructure analysis revealed that punching on the core layer of the sheet led to extra clad alloy on the side of the sample, which melted during heating and contributed to a greater measured melting peak area.

Effect of C:Ti atomic ratio on TiC morphology deposited by laser cladding process

In this paper, the effect of powder composition on TiC morphology and clad hardness using in-situ laser cladding process has been studied. Two atomic ratios, 45% and 55%, were selected for C:Ti, the first one of which has the potential to form TiC without formation of the preliminary Ti (α) phase. Fe percentages were 70. Results show that chemical composition affects the TiC morphology, TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45 at% to 55 at%, it is shown that the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad results in higher values of reinforcements in the clad, thus increasing the clad hardness. SEM and EDS analyses have been used to characterize the phases in the clad.In this paper, the effect of powder composition on TiC morphology and clad hardness using in-situ laser cladding process has been studied. Two atomic ratios, 45% and 55%, were selected for C:Ti, the first one of which has the potential to form TiC without formation of the preliminary Ti (α) phase. Fe percentages were 70. Results show that chemical composition affects the TiC morphology, TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45 at% to 55 at%, it is shown that the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad results in higher values of reinforcements in the clad, thus increasing the clad hardness. SEM and EDS analyses have been used to characterize the phases in the clad.

The Effect of Thermal Field on the Deposition of Fe-TiC on Carbon Steel Using Laser Cladding

In this paper, a numerical and experimental method is used to investigate the effect of thermal fields on the deposition of Fe-TiC using the laser cladding process. Since in laser cladding temperature distributions and consequent rapid cooling rates determine the microstructure and final physical properties of the deposited layers, a 3D time-dependent numerical model is used to simulate the cladding process parallel to experimental analysis. The numerical results are used to study the temperature distributions and their evolutions throughout the deposition process. The experimental and verified numerical outcomes are then employed to study the variations of the microstructures of the deposited material as well as correlation between the formed microstructures and temperature distributions across the deposition domain. The numerical and experimental investigations are conducted through the deposition of Fe-TiC on the substrate of AISI 1030 carbon steel using a 1.1 kW fiber laser. The experimental results confirm that by increasing the substrate temperature throughout the process the distribution of the TiC particles changes along with the deposited tracks and the TiC particles start forming clusters at the top of the clad.Copyright

Diamond reinforced metal coating using automated laser fabrication

Automated Laser Fabrication is an emerging advanced technology which penetrating in different aspects of manufacturing. This paper reports the automation laser fabrication of low-cost diamond tools. The engineered composition of the diamond and Cu-Sn-Ti are selected to address the issues, like-dissociation of diamond particles in metal matrix, good substrate-clad bonding etc. to ensure crack-free and pore-free deposition. The initial experiments pre-placed experiments show a promising trend. The process parameters are being optimized to obtain desired mechanical properties (like-hardness, wear resistance, toughness etc.) with sound metallurgical bonding. The paper will describe the optimization of process parameters along with material characterization.Automated Laser Fabrication is an emerging advanced technology which penetrating in different aspects of manufacturing. This paper reports the automation laser fabrication of low-cost diamond tools. The engineered composition of the diamond and Cu-Sn-Ti are selected to address the issues, like-dissociation of diamond particles in metal matrix, good substrate-clad bonding etc. to ensure crack-free and pore-free deposition. The initial experiments pre-placed experiments show a promising trend. The process parameters are being optimized to obtain desired mechanical properties (like-hardness, wear resistance, toughness etc.) with sound metallurgical bonding. The paper will describe the optimization of process parameters along with material characterization.

Repair of cemented carbide tools using laser cladding

This paper reports the laser cladding of various compositions of the Tungsten carbide (WC) and Cobalt (Co) for tool repair and refurbishing applications. The engineered compositions of the WC and Co were selected to address the issues, such as - partial melting of WC particles in the Co matrix, suppression the formation of hard brittle ternary eutectic phases to ensure crack-free and pore-free deposition.The initial experiments with a pulsed Nd:YAG laser indicated the promising trend. The process parameters are being optimized to obtain desired mechanical properties (like-hardness, wear resistance, toughness etc.) with sound metallurgical bonding. The paper describes the process and material characterization through various analyses.This paper reports the laser cladding of various compositions of the Tungsten carbide (WC) and Cobalt (Co) for tool repair and refurbishing applications. The engineered compositions of the WC and Co were selected to address the issues, such as - partial melting of WC particles in the Co matrix, suppression the formation of hard brittle ternary eutectic phases to ensure crack-free and pore-free deposition.The initial experiments with a pulsed Nd:YAG laser indicated the promising trend. The process parameters are being optimized to obtain desired mechanical properties (like-hardness, wear resistance, toughness etc.) with sound metallurgical bonding. The paper describes the process and material characterization through various analyses.