Method Of Cladding Research Articles

Research on rapid prediction method of laser cladding deposited layer state based on molten pool texture sequence

A texture sequence feature combining texture statistical characteristics with time series is proposed for rapid prediction of the state of laser cladding deposited layer. Texture features in the molten pool images are extracted using high-order dense texture descriptor operators and transformed into probability sequences with the aid of multi-cell histograms. Texture features are screened based on the types of points of interest to improve the sequence, enhancing the prediction accuracy and speed for deposited layer. For different types of points of interest, the optimal texture sequence obtained achieves an improvement of more than 6% in prediction accuracy for deposited layer state compared to the full-texture sequence. The proposed texture sequence features, when compared with molten pool image features, exhibit an average improvement in prediction speed of more than 17 times across different deep learning models. Overall, the results indicate that this method significantly improves prediction speed while maintaining accuracy, satisfying the requirements of high-speed monitoring in laser cladding.

Parameters optimization for single-track laser cladding based on MPA-SVR and A-NSGA-III

Laser cladding as an emerging surface modification technology, the morphology of the single-track cladding layer is directly affected by the process parameters. To obtain the ideal cladding layer morphology, it is necessary to build the mapping relationship between the process parameters and the morphology and optimize the process parameters. A method for predicting the morphology of the single-track cladding layer is proposed by using the support vector regression optimized by the marine predators algorithm. Then, the adaptive non-dominated sorting genetic algorithm III is used for process parameter optimization to determine the optimal process parameters of laser cladding. The results of the validation experiments show that the aspect ratio of the optimized cladding layer has been improved by 41.78%, the dilution rate has been improved by 22.30%, and the wetting angle has been reduced by 35.20%. The proposed process parameters optimization method of laser cladding can significantly improve the morphology of the cladding layer.

Laser surface cladding of metal parts

Laser surface cladding is a significant process used for improving and altering the surface properties of materials. Examples of these alterations are cladding of bulk materials with stronger and more expensive materials for enhancing the surface wear resistance, hardness, corrosion resistance, or creating magnetic property on non-magnetic material. In this paper, metal samples were laser processed by using the pre-deposited paste-powder method of laser surface cladding. Aluminium of Al6061 alloy and EN3B mild steel were chosen as the substrates, coated with the materials Inconel 718, Nitinol and 316 L stainless steel. A comparison of each of the sample's mechanical properties through specific wear rate and microhardness was conducted. It was found that all samples had improved microhardness compared to that of their substrates. Furthermore, all aluminum base samples had significantly improved wear rates by at least 72%. Microhardness increase of 3.2 and 1.5 times on the Al and steel samples cladded with Inconel and Nitinol respectively. The cross-section of all the processed samples' microstructure was examined under a scanning electron microscope. Results showed the interface of the clad layer, substrate, and a clear heat-affected zone of the mild steel samples.

Modeling and Optimization Method of Laser Cladding Based on GA-ACO-RFR and GNSGA-II

Modeling and Optimization Method of Laser Cladding Based on GA-ACO-RFR and GNSGA-II

Microstructure, toughness, and tribological properties of laser cladded Mo2FeB2-based composite coating with in situ synthesized WC and La2O3 addition

Mo2FeB2-WC-La2O3 composite coatings were prepared using a preplaced method of laser cladding. The forming quality, microstructure, distribution of La, microhardness, fracture morphology, fracture toughness, and tribological properties were examined. The effect of La2O3 on the microstructure and properties of the coatings was analyzed. The results showed that the metallurgical bonding between the coating and substrate was significantly improved. La2O3 had no significant effect on the phases of the composite coatings. The microstructure growth of the La2O3 coating had no obvious direction and a block-like structure. The microstructure was initially refined and then coarsened with an increase in La2O3; La was found to exist at the Mo2FeB2 phase grain boundaries. The microhardness of the Mo2FeB2-WC coating was 1584.6 HV0.5. The microhardness of the composite coating that contained 0.3 wt% La2O3 reached 1494.7 HV0.5; its coefficient of friction (COF), wear rate, and fracture toughness were 0.31, 3.13 × 10−5 mm3/Nm, and 14.35 MPa·mm1/2, respectively. The crack resistance of the composite coating was the highest at 0.3 wt% La2O3 addition. The wear mechanisms of the coatings containing La2O3 were typical abrasive wear, and the coating without La2O3 was a combined mechanism of slight adhesive and abrasive wear. The coating exhibited an evident brittle fracture morphology.

Cladding phase change materials in freezing and chilling zones of household refrigerator to improve thermal performance and environmental benefits

The rapid change in the lifestyle of people makes refrigerator an inevitable appliance in every home and its sales are increasing every year. Since refrigerators account for the major share of energy consumption in homes, many technologies are adopted to improve its energy efficiency for environmental protection. The favourable properties of phase change material (PCM) in terms of its energy efficiency, attracted the use of the same in refrigerators. Cladding of PCM on evaporator and condenser showed improvement in overall performance of the system. In most of the previous studies, single PCM was selected for this purpose. Since a domestic refrigerator maintains different temperatures inside its compartments, cladding of multiple PCMs with freezing temperatures close to freezer and chiller compartments was considered for the experimental study. The energy and exergy efficiencies, along with economic and environmental benefits were studied to validate the proposed method of PCM cladding in a household refrigerator. To identify the appropriate PCM pair and cladding positions, seven configurations of PCM arrangements, represented as C1, C2, C3, C5, C5, C6 and C7 were used in the experimental study. Among the configurations, C5 and C7 showed better performance with 18.5 % reduction of energy consumption. The arrangements also complemented in reducing the number of ON/OFF cycles. Compared to conventional system, the proposed C5 and C7 configurations can reduce the total equivalent warming impact by 18.56 % and 14.43 % respectively.

ВЫБОР РАЦИОНАЛЬНЫХ РЕЖИМОВ ПОЛИРОВАНИЯ ПЛАКИРОВАННЫХ ХРОМОВЫХ ПОКРЫТИЙ

As a result of experimental and statistical modeling, dependencies were obtained that establish the effect of polishing modes (the number of passes of the polishing wheel, the value of the wheel tightness) on the roughness and thickness of the chrome coating obtained by the method of deformation cladding with a flexible tool. It was found that within the selected intervals of variation of the factors, an increase in the tightness of the polishing wheel and the number of passes of the wheel leads to a decrease in both the parameter of the roughness Ra and the thickness of the coating, however, with different degrees of intensity. The number of passes of the polishing wheel has a decisive effect on the value of the surface roughness of the clad layer after polishing. The effect of polishing modes on the thickness of the cladded coating is more complex, since it is demonstrated both in the individual comparable influence of both factors and in their interaction. The optimal modes of polishing of hydraulic cylinder rods subjected to chromium plating by the method of deformation cladding with a flexible tool have been determined. After the experimental check in the conditions of JSC “Minsk Automated Lines Plant named after P.M. Masherov” (Republic of Belarus), the established technological modes of polishing were added to the technological process of chromium plating of rods. It confirms the effectiveness of using the calculated dependencies.

Abrasive wear of metal surface modified with mineral particles

The resistance of mineral coatings created on the surface of specimens of 20X13 steel (Russian analogue of steel 20Cr13 (EU)) modified with ultradispersed mineral particles to abrasive wear during friction against fixed particles was determined, and the wear parameters of layers modified with mineral particles were compared with the parameters of surface layers created by laser cladding of alloys of different compositions. The studies were carried out on an experimental setup for testing abrasive wear under a static load of 60 N and 160 N and determined the weight wear, the average wear rate and the average wear rate of the surface layer of three samples with different mineral coatings. According to the results of measurements at a pressure on the wear surface of 0.5 MPa, a sample was determined with an indicator of weight wear comparable to a coating made of cobalt alloy, created by the method of laser cladding and about four times inferior in this indicator, to a coating of a nickel alloy, created by the method of laser cladding and tool steel. The practical use of various methods of protecting parts from abrasive wear is determined, along with the physical and technical characteristics of the layers, by the economic feasibility in specific operating conditions.

The Forming Control Method of Multi-Track Laser Cladding on Curved Surface

This paper investigated the correlation between the processing parameters and the properties of clad deposited by laser cladding on a curved surface. Mathematical models relating the processing parameters (laser power, scanning speed, gas flow, and overlap ratio) and clad properties (flatness ratio and pore area) were established by central composite design. Analysis of variance and experimental validation confirmed the validity of the models. The results indicated that the flatness ratio was negatively influenced by the larger scanning speed, gas flow, and overlap ratio, while the pore area was enlarged by the increasing of scanning speed, and increasing the overlap ratio lead to the pore area reducing at first and then increasing. Optimized processing parameters were obtained under the target of maximizing the flatness ratio and minimizing the pore area. The developed mathematical models enabled predicting the flatness ratio and pore area with optimized processing parameters. The validation experimental result verified the prediction accuracy of the models and displayed target improvement compared with the original central composite design. The results provide theoretical guidance in multi-track laser cladding on a curved surface for the prediction and control of the geometric characteristics of the coating and the optimization of the processing parameters. This research outcome provides guidance for the coating deposition application in crankshaft surface coating or surface restoration, rotary parts coating deposition, or complex shape tool manufacturing. It also forms the fundamental basis for the extensive application of multi-track laser cladding on curved substrates in the additive manufacturing industry.

Research on microstructure of copper coatings on AlN ceramic surface by laser cladding and brazing

The preparation of Cu-based coatings on AlN ceramic surface was accomplished by laser cladding and brazing technology. The Cu-based coating was prepared by both copper powder and titanium powder on ceramic surface. The microstructure and properties were tested by x-ray diffraction, metallurgical microscope, scanning electron microscope, energy dispersive spectrometer and microhardness tester. The novelties of this paper in the method of laser cladding and brazing were used to prepare Cu-coating on ceramic surface and the addition of Ti could improve the properties of Cu-based coating. The addition of Ti improved the wettability of ceramic surface. According to the results of EDS, Ti could better get into the Cu-based coating and formed metallurgical bonding in the laser cladding. The microhardness of laser cladding was higher than brazing, which could be concluded that it was due to the rapid cooling rate during the laser cladding could restrain grain growth and element segregation.

Formation of wear-resistant copper-bearing layers on the surfaces of steel substrates by non-vacuum electron beam acladding using powder mixtures

By using the method of non-vacuum electron beam cladding, copper-bearing surface layers have been obtained on mild steel substrates. These layers possessed enhanced wear resistance under sliding friction compared to the substrate material. Metallographic and TEM investigations revealed that copper in cladding layers was in the form of nanoscale inclusions distributed in the ferrite matrix as well as in the form of large precipitates in the interdendritic space. The latter is an undesirable effect that significantly reduces the reliability of the material. Technological experiments aimed at dilution of the cladding material with aluminium or carbon in order to reduce the amount of copper precipitate in the interdendritic space and, consequently, to improve the quality of the cladding layers have established that the latter approach is the most efficient. The addition of aluminium, which increases the solubility of copper in the iron, contributes to the formation of the embrittling intermetallic phase (AlFe) in the ferrite matrix. When applying cladding using a mixture containing copper, iron, and carbon, the structure of hypoeutectic cast iron with nanoscale precipitates of copper in ferrite and cement forms in the surface layer. The wear resistance of such layers is one order of magnitude higher than that of the base material.

Fractographic Study of Destruction of Composite Coatings After Bending Tests

The paper presents results of fractographic studies of fracture of specimens with coatings obtained by the method of nonvacuum electron-beam cladding of refractory powders on a steel substrate after conducting three-point bending tests. It has been established that brittle fracture of the coating with cracking occurs during specimen bending. The fracture is dendritic in character due to the cast dendritic structure formed in the deposited layer. The important roles of the dendrite grain sizes and of the volume fraction of eutectics have been revealed and justified. The influence of the eutectic volume fraction on the microhardness and strength of the coating has been established.

Technology support for the supply of an element of the coating material during cladding with a flexible tool

The article considers the issue of improving the quality of machining of engineering products when using the method of deformation cladding with a flexible (wire) tool (wire brush). The essence of this method is to combine the processes of plastic deformation from impacts of wire brush with coating for various functional purposes. The design of the feed device has been developed, which allows controlling the necessary clamping force of the coating material element (MCE) to the wire tool. The control of clamping force provides temperature stabilization in the contact between the MCE and the tool and allows to increase the uniformity of coating formation on the workpiece. The coating material is set with eccentricity relative to the axes of the brush, which makes it rotate about its axis during operation, ensuring its uniform wear. This feed device is easily dismantled, which provides a quick replacement of the MCE.

Structural studies of surface-alloyed layers of the Cr-B4C system, formed on Ti-6Al-4V titanium alloy

The paper presents studies of the structure of surface-alloyed layers obtained by the method of non-vacuum electron-beam cladding of the Ti-Cr-B4C and Cr-B4C powder mixture systems. Structural analysis allowed to identify the dependence of the initial powder portion on the shape and size of the phases formed. It is noted that the presence of titanium (10 wt. %) in the composition of the surfacing mixture leads to the formation of large primary crystals of titanium carbide and boride. The absence of titanium contributes to the formation of chromium carbide coating and small eutectic particles on the grain boundaries on the surface.

Al2O3 eliminating defects in the Al coating by laser cladding to improve corrosion and wear resistance of Mg alloy

AbstractAlthough Al produces a solid metallurgical bonding with Mg alloy substrates, micropores or crevices in the Al coating can reduce the resistance of Mg alloy to corrosion. In this study, a composite coating with a defect‐free microstructure was prepared on the AZ31 Mg alloy substrate by introducing Al2O3 into the Al matrix via the method of laser cladding. On the one hand, Al2O3 with thermal insulation had a low thermal expansion coefficient and was not very prone to voids during laser melting. On the other hand, Al2O3 particles with a small size acted as the filler in the micropores or crevices. The Al/Al2O3 coating exhibited a smaller current density (2.1 × 10−6 A/cm2) in comparison with those of bare substrate and Al coating (158.4 × 10−6 and 3.1 × 10−6 A/cm2, respectively), which was mainly ascribed to the pore‐free microstructure and high resistance to corrosion of Al2O3 phase. A favorable microhardness value of 95.3 HV was achieved for Al/Al2O3 coating, approximately 1.8 times higher than that of Al coating (52.8 V), which was mainly ascribed to the dispersion hardening of Al2O3 phase. Meanwhile, the Al/Al2O3 coating significantly reduced wear volume from 2.8 mm3/m of Al coating to 0.4 mm3/m, showing great potential for weight reduction applications.

Determination of mechanical properties of coatings obtained by non-vacuum electron beam cladding

A study on the mechanical properties of composite materials obtained by the method of non-vacuum electron-beam cladding of refractory powders on a steel substrate was carried out. The mechanical properties of composite with coatings were investigated by a three-point bending test at room temperature. The strength of the obtained composite was 4.5-6 times higher compared to that of low carbon steel depending on the deposition modes.

Investigation of Crystallization Process of a Single Crystal Nickel-Based Alloy during the Laser Multilayer Cladding

The article shows the results of multilayer laser cladding of heat-resistant single crystal nickel-based alloy ZhS32-VI (CSMX-4 analogue). The influence of the main technological parameters on geometry and microstructure formation of deposited beads was investigated. Based on obtained dependencies, the regression equations are compiled for describing the shape of bead and the ratio of directional and equiaxial crystallized sections. The obtained dependencies of regime parameters nomination allow restoring the gas-turbine blades by the method of laser cladding.

Study of various types cladding and the evolvement of the techniques through years and the future scope – A review

In this study the various types of cladding and the various advantages of using different materials. Today there are many different methods for cladding, but every type has its own advantage. Cladding has evolved from various industrial applications and over a decade there are many improvements in the field. Laser cladding is the advanced method of cladding which is the additive method of clad, and it is found to be economical and efficient method of cladding. To improve the life of the clad, high intensity laser beam is used to fuse the substrate with the metal in melting process.

The Formation of Composite Coatings with High Hardness with High-Speed Heating

The article dwells on the developed method of induction cladding of refractory compounds based on carbide-boride products (Ti,Cr)B2+W2B5+B4 and TiC+W2B5+FeV using a special charge material in the condition of high-speed heating by high frequency current. It has been established that during induction heating the cladding layers are formed as per the scheme where the refractory component is partially diluted in the bonding molten metal, it does not dissociate and forms strong matrix-reinforced structures with high resistance to wear. The article describes the efficiency of their use in case of abrasive wear.

A New Method of Selective Laser Cladding

A new approach to selective laser cladding using conical laser beams has been elaborated. The initial round laser beam is divided into two or more circular beams with regulated distribution of the laser power between them. The circular beams are converted into conical beams that are focused separately on the surface and on different areas of the deposited material for their efficient heating. The delivery of laser energy into the powder stream is very effective because it provides a complete uniform absorption of laser energy in a dense powder stream (104–106 cm–3). Under wire deposition, substrate heating reduces residual stresses due to temperature gradients and compensates for heat loss from the deposition zone by thermal conduction. The required power density for melt contact formation is significantly reduced.