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In cutting, when an insert is subjected to a large mechanical-thermal shock load, a large bending moment may be produced in the front of the insert, causing tensile stress concentration and insert breakage. In this paper, stepped structures with different gradient parameters are designed in the surface layer of the shim used under the insert to reduce the bending moment and the stress concentration in the insert. The simulation model of the insert-shim system was established, and finite element simulation analysis was carried out for the insert with and without the prefabricated crack. The effects of stepped shims with different gradient parameters on the stress, strain, bending moment of the insert, and crack propagation at the crack front in the inserts were investigated under static loading condition. Interrupted cutting experiments were carried out using the stepped shims. The simulation results show that the stepped shims with gradient parameters of 0.005 mm–0.015 mm can effectively reduce the bending moment, maximum tensile stress, and maximum tensile strain of the inserts; the stepped shims with gradient parameters of 0.005 mm–0.015 mm can significantly reduce the maximum tensile stress and the stress intensity factor at the front of the cracks and reduce the internal propagation of the cracks. The experimental results show that the stepped shims with gradient parameters of 0.005 mm–0.015 mm can effectively prevent insert breakage in the cuttings with the large depth of cut and low cutting speed and reduce the degree of insert breakage in the cuttings with the small depth of cut and high cutting speed.

In machining processes, the high temperature and stress can lead to plastic deformations of the workpiece material. Thermomechanical loading has a significant impact on the microstructure of the machined surface, including grain deformation, recrystallization, and refinement. Among these factors, grain refinement plays a crucial role in determining the mechanical properties of the materials. To investigate the mechanism of grain refinement on the machined surface of Inconel 718 at different cutting speeds, the experiments and finite element simulations were conducted. The microstructural characteristics were quantitative analyzed, including grain size, grain boundary distribution characteristics, average orientation (KAM), and geometrically necessary dislocation (GND) density distribution. The mapping relationship between the multi-physical fields (equivalent plastic strain, temperature) during cutting and the microstructural evolution of Inconel 718 was established. The research indicated that the increasing the cutting speed leads to a higher degree of grain refinement. At a cutting speed of 450 m/min, the maximum grain refinement is achieved with an approximately grain size of 2.48 μm. The contribution from plastic deformation (dynamic recuperation) gradually increases while high temperature remains dominant as factors influencing grain refinement. Conversely, the equivalent plastic strain becomes the primary factor contributing to grain refinement, with a gradual increase in the proportion due to dynamic recrystallization at cutting speeds of 250 m/min and 350 m/min.

Laser cladding is being employed for repairing high-end components including thin-walled parts. The heterogeneous interface between cladding layer and substrate can exacerbate cutting vibration during subsequent machining, becoming a bottleneck in remanufacturing thin-walled parts. This paper focuses on exploring the effect of interfacial structures on cutting vibration suppression in side milling of laser cladded layer on thin-walled parts. First, the interfacial structure was proven to be effective for suppressing cutting vibration by increasing modal damping, although the stiffness shows a decreasing trend. Among different interfacial structures, triangular structure showed the best role in cutting vibration suppression, followed by rectangular, semi-circular, and trapezoid. Then, the effects of different structural parameters on cutting vibration suppression were further analyzed based on a Taguchi design. The results showed that the cutting vibration decreases with the smaller interfacial shape factor, larger depth and smaller spacing of interfacial structures. The interfacial structure would be optimal when the interfacial shape factor is 0.06, the interfacial depth is 3.0 mm, and the spacing is 0 mm. As a result, the cutting vibration during milling was reduced by 55.28 %. These findings provide a theoretical basis for high-quality remanufacturing of the thin-walled parts.

During subsequent machining of laser cladded workpiece, the stress transferred in depth direction is different with conventional cast workpiece due to the geometrical discontinuity, resulting in the stress difference and strain discontinuity at the interface between the cladding layer and substrate. Elastic and plastic deformation will occur in the cladding layer and substrate, respectively, which ultimately reduces the service life of the cladded workpiece. In this study, the stress and strain evolution in subsequent machining of laser cladded workpiece was investigated using an orthogonal cutting model by finite element method. A dimensionless thickness ratio between uncut chip thickness and cladding layer thickness was set and the maximum thickness ratio without equivalent plastic strain (PEEQ) discontinuity at the interface was determined. In addition, the results indicated that the maximum thickness ratio first decreased and then increased with the increase of cutting speed, while increases with the increase of the yield strength of substrate. The synergetic effects of thickness ratio, cutting speed and yield strength of substrate on the strain discontinuity at the interface were also investigated based on Taguchi method. The optimal combination of parameters is determined based on the regression model and divided into areas with considering machining efficiency as well. The map of cutting configurations facilitates the selection of proper machining parameters in order to estimate the strain discontinuity in machining laser cladded workpiece, ensuring a better service life of the workpiece.

Improving the surface integrity of laser cladded layer via burnishing is an important research topic in remanufacturing field. However, the initial surface roughness condition induced by mechanical machining generates great influence on the strengthening mechanism of subsequent burnishing. In this study, the effects of ultrasonic-assisted burnishing (UB) and ultrasonic-assisted warm burnishing (UWB) on the surface integrity of laser cladded layer were analyzed when treated on different surface conditions obtained by turning with different feed parameters. The results indicated that both the UB and UWB treatments would cause great improvements in microhardness, surface roughness including height and functional parameters, and residual stress of the laser cladded layer when compared to those by turning. First, the severe plastic deformation in UB and UWB treatments counteracted the thermal softening effect in turning process, so that the machined surface could maintain high hardness. Second, UB treatment reduced the roughness by 70% compared with turning, while the surface roughness after UWB treatment was even 30% lower than that obtained by UB. Third, the tensile residual stress shifted to deep compressive state by both UB and UWB treatments, though the thermal load in UWB generated a negative effect on generating compressive residual stress. According to the surface integrity evaluation results by radar diagrams, turning with feed f= 0.2 mm/r and UWB is preferred in machining of the laser cladded layer for enhanced surface integrity. On the basis of this research, it is expected to achieve the purpose of high-efficiency and high-quality cutting of the laser cladded layer.

Microcracks can form on the surface or inside an insert during forming or cutting processes. These microcracks tend to expand rapidly under impact loading, eventually leading to tool fracture and failure. Fracture and breakage of inserts cause significant limitations to the improvement of processing efficiency and safe production. This study investigated the effects of shim stiffness (using Young's modulus) on the stress distribution in the insert and at the crack tip under static and dynamic (impact) loading conditions, thereby providing a theoretical basis for correctly designing and selecting inserts for indexable tools. The extended finite element method (XFEM) was used to develop a 3D simulation model for an insert–shim system. The model was used to study crack initiation and expansion in the insert for different rigid shims under static and dynamic loading. Analyses of the crack tip stress intensity factor, the maximum principal stress, the strain, and the angle and direction of crack deflection were performed. Additionally, interrupted cutting experiments were conducted with cemented-carbide tools for four rigid shim materials. It was concluded that under static loading conditions, a weakly rigid shim reduced the crack tip stress intensity factor and the maximum principal stress, thus reducing the probability of insert fracture and that the stiffness of the shim has no effect on the angle of crack deflection on the insert surface. The shim stiffness has a more obvious effect on the crack propagation length and internal propagation direction during dynamic loading, and a weakly rigid shim increases the deflection angle as the crack expands inside the insert, thereby reducing the downward fracture length.

Covalent Organic Frameworks (COFs) are widely used for photocatalysis but limited by the aggregation of the catalysts, which limited the mass transfer. Herein, corn stalk cores were used as the substrate, and two kinds of biomass based COFs with different electronic structures of thiophene (C@SCOF) and pyridine (C@NCOF) were in-situ fabricated uniformly on the surface of the substrate. In this way, COFs expose more active sites rather than embedding in the agglomerated structure. Biomass based COFs, especially C@SCOF, exhibit a hierarchical porous structure containing micropores and macropores, which offer fast mass transfer channels for the catalytic and adsorbed substrates. Therefore, the biomass based COFs utilized more efficiently to achieve higher photocatalytic performance. The C@SCOF with D-A structure displays stronger photoresponse and lower impedance, which promote the dissociation of a photogenerated exciton and carrier separation efficiency, resulting remarkable photocatalytic performance for oxidation of benzylamine coupling reaction. This work could guide the design and preparation of biomass-based hybrids with promising performance.

During subsequent machining of laser cladded workpiece, the stress transferred in depth direction is different from the conventional cast workpiece due to the geometrical discontinuity, resulting in the stress difference and strain discontinuity at the interface between the cladding layer and substrate. Distinguishing from the traditional finite element method model, this paper establishes a model with an inclined interface to investigate the thickness ratio, i.e., the ratio of the removal thickness in subsequent machining to cladding thickness on the machining-induced stress and strain. The results show that the maximum thickness ratio is 0.352 when the removal thickness is 0.1 mm. The change in interfacial shear stress energy dissipation due to interfacial inclination makes this result 22.8% lower than a traditional model with a horizontal interface. With the help of the presented model, the effect of removal thickness on machining-induced stress and strain evolution was investigated. The results show that an increase in the removal thickness will lead to an increase in machining-induced stress and strain. The stress difference and strain increment at the interface increase proportionally with the removal thickness, implying that variations in removal thickness will have a consequential impact on the maximum thickness ratio. Thus, the interaction of material removal thickness and thickness ratio on PEEQ increment at the interface was further analyzed. The response surface results indicate that an increase in the removal thickness leads to a corresponding increase in the maximum thickness ratio, albeit with a minor degree of influence. Therefore, the challenge of fixing the maximum thickness ratio in actual machining due to multi-step processes can be resolved through micro-adjustments. Simultaneously, in engineering applications, workpiece surface defects exhibit varying depths and require different removal amounts after cladding. This study provides further theoretical guidance for repairing and remanufacturing surface defects with diverse depths.

The machinability of the Al–Si alloys becomes worse with the Si content increasing. This article explored the influence of Si content on the machinability including cutting forces and chip breakability in machining the Al–Si alloys. The change in machinability of the Al–Si alloys with different Si content attributes to the evolution of microstructure. The cutting forces when cutting hypoeutectic Al–Si alloys are higher than the hypereutectic alloys because only Mg2Si (β-phase) precipitations are formed in the former one versus cooperative precipitation of Al2Cu (θ-phase) and Mg2Si in the latter. With regard to hypereutectic Al–Si alloys, cutting force components decrease with the increase in Si content due to the formation of brittle primary Si, which induces the initiation of cracks in material removal process. Moreover, the cutting stability of Al–Si alloys is improved with Si contents in the range of 12–18 wt%, while deteriorates for the Si content of 25 wt%. Besides, the chip breakability is improved due to the increase in eutectic silicon in hypoeutectic and eutectic ranges and because of the formation of block-shaped primary Si for hypereutectic alloys. The optimization of Si content is 12–18 wt% with cutting speed not less than 150 m/min.

Diabetic kidney disease (DKD) is one of the main complications of diabetic microangiopathy. The pathogenesis of DKD is very complex, including autophagy, inflammation, oxidative stress. Although a series of treatment intervention have achieved certain results in the treatment of diabetic nephropathy, still cannot reverse the kidney injury of diabetic nephropathy. The kidney is one of the most important organs of energy metabolism. Renal function is highly dependent on phagocytosis of mitochondria, and aberrant or defective autophagic mechanisms are central to the pathology of many renal diseases. Under high glucose conditions, mitochondrial fragments accumulate in the kidney, suggesting that mitochondrial clearance mechanisms may be attenuated with changes in mitochondrial transformation mechanisms. However, the exact mechanism of mitophagy regulation in DKD has not been elucidated. Recent advances in autophagy have renewed interest in these signaling pathways and molecules in the pathogenesis of DKD. Investigating autophagy and its associated signaling molecules may provide potential unique targets for therapeutic intervention in DKD.

Laser cladding is commonly used to improve the wear and corrosion resistance of the substrate material. However, mechanical machining is necessary, because the surface irregularities and poor surface roughness after laser cladding. It is urgent to investigate the effect of machining on the corrosion resistance of the laser cladded layers, so as to avoid the reduction of corrosion resistance due to the use of inappropriate cutting parameters. In the present study, the influence of turning-induced surface roughness on the corrosion resistance from the viewpoint of corrosion potential was analyzed first. The corrosion potential is the result of the effect of roughness height parameters and functional parameters. Second, the effect of the machining and subsequent burnishing on the corrosion resistance was analyzed by comparing the corrosion behaviors of the turned and burnished surfaces. The polarization resistance is critically increased by subsequent burnishing. Third, the sensitivity of the machined surface on corrosion resistance was analyzed by EIS method. The strengthening mechanism of machining and subsequent burnishing on the corrosion resistance was determined. On the basis of this research, it is expected to be used to guide the selection of appropriate feed parameter in prior turning to improve the strengthening effect of subsequent burnishing, and then, to improve the surface integrity and corrosion resistance of the laser cladded layer.

Corrosion resistance of machined surface and its correlation with surface roughness have been the important concerns for sustainability of the final products. However, the pitting corrosion of laser-cladded Fe–Cr–Ni layers by turning exhibits susceptibility to surface roughness characteristics. In present study, the generation mechanism of pitting susceptibility by turning and the effect of burnishing on decreasing the pitting susceptibility were explored. To this end, a theoretical model of the potential difference between roughness peaks and valleys was established with considering the functional parameters of the surface roughness. Then, the correlations between the potential difference and pitting characteristics including pitting depth, width and area were analyzed in order to reveal the generation mechanism of pitting susceptibility. The occurrence of pitting corrosion could be predicted by the local potential difference, which was higher at the location where pitting corrosion would occur while lower where pitting corrosion did not occur. Finally, the influence of each functional parameter of surface roughness on the potential difference was analyzed using the proposed model, with which the machining schematics were discussed. On the basis of this research, it was expected to improve the corrosion resistance of the claddings by turning and subsequent burnishing process chain.

On earth-space paths, by applying a modification of the Rytov method that incorporates spatial frequency filter function under strong atmosphere fluctuation conditions, a tractable model is developed for the scintillation index of infrared laser Gaussian beam wave that is valid under moderate-to-strong irradiance fluctuations. At Infrared band, based on ITU-R C2nmodel, the scintillation indexes for collimation laser beam are predicted by this analytic model. The results agree with theoretic expected scintillation. This scintillation model can be converted into a plane or a sphere wave scintillation index model on earth-space paths, and also reduced to a Gaussian beam wave model on horizontal sight paths of invariable C2n.

The hydraulic support column of comprehensive mining equipment is the most important part, subjecting to corrosion, wear and collision. The scrapped columns are restored by laser cladding to replace plating process for enhancing service life. All that is required after laser cladding is subtractive machining to improve the surface quality of the laser cladded coatings. This work focused on the remanufacturing machining strategy for re-contouring the laser cladding restored columns. First, surface roughness model of the laser cladded coatings by turn-burnishing was presented based on the surface generation mechanism. Then the effect of turning-induced roughness level on the surface roughness improvements by subsequent burnishing is addressed. Results indicated that the reduction of surface roughness by burnishing showed positive correlation with the feed in initial turning with conventional inserts, while was negatively correlated with the feed in initial turning with wiper inserts. In addition, the initial turning-induced surface roughness level generated great influence on the residual stress improvement in subsequent burnishing. Based on the findings, proper remanufacturing machining strategies for re-contouring the laser cladding-restored hydraulic support columns were presented.

Laser cladding has been commonly utilized for restoring high value-added parts. However, the poor surface quality becomes key technological barrier which restricts its widespread applications. In the paper, re-contouring strategies by machining method are explored for minimal energy consumption as well as required surface roughness. Firstly, the effect of structural characteristics of the laser-cladded workpiece on specific cutting energy was explored by means of layer-by-layer turning and orthogonal cutting. Results indicated that the specific cutting energy increased, and the machining chatter/vibration exacerbated with decreasing coating thickness under fixed cutting parameters. The reason can be summarized as a result of the effect of elastoplastic deformation behavior across the interface. Then, the influences of depth of cut and feed on specific cutting energy in finish turning were addressed. Results indicated that the specific cutting energy reduced with increasing depth of cut and feed in the form of power functions. In addition, energy efficiency decreased with an increase in uncut chip thickness and cutting speed. On basis of this work, large feed and low cutting speed with the adoption of wiper inserts were recommended for minimizing energy consumption within surface roughness requirement.