Metal porous materials are versatile, functioning as both structural and functional materials due to their unique properties like energy absorption, distinct from solid metals. These materials are utilized extensively in engineering due to their vital physical and mechanical characteristics, influenced by their base metal, manufacturing methods, porosity, and pore architecture. Particularly, their tensile properties are crucial, with research indicating that increased porosity leads to reduced strength and stiffness. Studies have shown that sintering temperature impacts the tensile strength of these materials, with higher temperatures leading to stronger, coarser connections between components and thus higher tensile strength.
Various approaches have been explored for crafting metal porous materials, such as creating aluminum foams with controlled pore size and shape, blending and sintering high-porosity copper foams with spherical copper powder, and employing spherical carbamide as a spacer to achieve uniform pore distribution in stainless steel foams. Novel methods also include solid-state sintering of copper fibers to produce a sintered sheet with a three-dimensional network and combining titanium powder with rice husk particles to create titanium-tantalum composites with specific porosities.
This study introduces a new technique for producing porous stainless steel strips by rolling stainless steel wire mesh and powder together. Following the rolling process, these strips were folded, pressed, and vacuum sintered to create a porous stainless steel wire mesh and powder composite (SWMPC) plate. The investigation focused on how rolling reduction, powder box gap, folding layers, and sintering conditions affect the material’s porosity and tensile strength.
Preparation of new porous metal materials using stainless steel wire mesh and powder composite
Preparation of Materials
At the outset, the selection of materials plays a pivotal role in the success of this venture. The foundation is laid with the use of 304 stainless steel Dutch wire mesh, chosen for its superior mechanical properties, which are a direct result of its unique weaving technology. Distinguished by its fine mesh count of 400 and the strategic variation in wire diameter between the warp and weft, this mesh offers an optimal blend of density and strength. This choice is further complemented by the selection of 304 stainless steel powder, its irregular shape procured through water atomization, enhancing the composite’s overall structural integrity.
Design of Experiments
Delving into the experimental design, the preparation process is meticulously crafted, beginning with the arrangement of a sophisticated rolling machine. This machine, capable of exerting a formidable force of 240 tons, plays a critical role in compressing the composite materials into a cohesive, porous, thin strip. The precision in adjusting the gaps between rollers and the innovative use of an auxiliary device underscores the importance of detailed control in achieving the desired porosity and thickness.
In an elegant choreography of material science, the wire mesh and powder are layered, then driven forward by the relentless force of the rollers. The aluminum plate and powder box, integral to the process, ensure an even distribution of the powder across the mesh, setting the stage for the transformation of these raw materials into a unified strip.
The journey from strip to plate is not without its challenges. The need to eliminate any gaps between layers leads us to employ an extruder, which, with its impressive pressure of 315 tons, compresses the folded strip into a denser form. The culmination of this process is achieved through vacuum sintering, a critical step that not only solidifies the composite but also meticulously preserves its porous structure, ensuring that the end material embodies the desired characteristics of strength and permeability.
Experiment of Air Permeability
The quest for understanding does not end with the creation of the porous plate. The experimental exploration of air permeability, employing compressed air as a test medium, reveals critical insights into the material’s functional capabilities. Through a custom-designed experimental setup, the flow of air through the material is meticulously measured, allowing for the calculation of the relative permeability coefficient—a key indicator of the material’s potential applications.
Characterization
With the materials prepared and their permeability tested, the next stage focuses on characterization. Employing a scanning electron microscope, the intricate microstructure of both the thin strip and the porous plate is brought into sharp relief, revealing the finesse of the manufacturing process and the material’s structural nuances. The porosity, a critical factor in the material’s performance, is quantified using the mass volume method, offering a precise measure of the void spaces that contribute to the material’s unique properties.
Relative Permeability Coefficient
In the realm of engineering, where practicality reigns supreme, the relative permeability coefficient emerges as a vital measure. Calculated through the application of Darcy’s simplified formula, this coefficient offers a quantifiable insight into the material’s ability to facilitate fluid flow, a characteristic that is as much a testament to the material’s innovative preparation as it is to its potential utility in a multitude of applications.
Tensile Properties of the Porous Plate of Stainless Steel Wire Mesh and Powder Composite
The journey into understanding the tensile properties begins with an analysis of the stress-strain curves, obtained from samples with varying porosities and preparation parameters. A particular focus is given to a sample designated as No. S4, showcasing a porosity of 15.35%. This specimen underwent a rigorous preparation process, including specific adjustments to the gaps of the rollers (d1) and powder box (d2), along with a precise folding layer count and a carefully controlled sintering temperature.
The stress-strain curve for this sample is dissected into four distinct stages, each corresponding to a unique deformation behavior. The initial phase, known as the elastic deformation stage, is characterized by a linear relationship between stress and strain, abiding by Hooke’s Law. This phase transitions into a complex stage where elastic and plastic deformations coexist, attributed to the material’s heterogeneous porosity and the varying degrees of metallurgical bonding. As the material stretches, regions of weaker metallurgical quality deform first, leading to a stress redistribution that enables other areas to yield to plastic deformation.
Advancing further, the material enters a purely plastic deformation stage, where the strain hardens, enhancing the material’s resistance to further deformation. This stage is pivotal, as it marks the material’s capacity to withstand stress up to its ultimate tensile strength before succumbing to fracture. The final stage, fracture, is rapid, with macroscopic cracks initiating in areas of weak metallurgical bonding, leading to a sudden decrease in stress and eventual material failure.
Further investigations involve samples subjected to different sintering temperatures. The findings highlight a critical relationship between the sintering temperature and the material’s tensile properties. Lower sintering temperatures result in poorer metallurgical bonds and more pronounced delamination, significantly impacting the tensile strength and ductility. Conversely, higher sintering temperatures enhance the metallurgical bonding between the wire mesh and the powder, thereby improving the material’s strength and elongation capabilities.
The influence of the powder box gap (d2) on the material’s porosity and mechanical properties is also examined. A smaller gap leads to a higher powder density upon rolling, resulting in reduced porosity and enhanced mechanical properties. This correlation underscores the importance of precise control over the preparation parameters to tailor the material’s properties to specific applications.
Additionally, the impact of the number of folding layers on the material’s tensile properties is explored. Surprisingly, the porosity remains relatively unchanged with an increase in the number of layers, suggesting that the porosity is predominantly determined by the initial preparation of the thin strips. However, samples with a higher number of layers demonstrate slightly improved tensile strength and elongation, likely due to the increased reinforcement provided by the additional layers of wire mesh.
In conclusion, this comprehensive study sheds light on the complex interplay between the preparation parameters and the tensile properties of porous plates made from stainless steel wire mesh and powder composites. The findings not only contribute to a deeper understanding of the material’s behavior under tensile loads but also open avenues for optimizing these composites for various engineering applications. Through meticulous experimentation and analysis, this research underscores the potential of these novel porous materials in pushing the frontiers of material science and engineering.
Wrap Up
In the quest to unveil the potential of stainless steel wire mesh-powder composites (SWMPCs) for engineering applications, this study embarked on an explorative journey, meticulously crafting porous plates with varying porosities and examining their tensile properties. Through a comprehensive experimental setup, involving composite rolling, folding, pressing, and vacuum sintering, SWMPCs with porosities ranging from 10% to 30% were successfully fabricated. The findings from this research provide critical insights into the intricate balance between porosity, mechanical properties, and permeability, paving the way for future innovations in material science.
A pivotal revelation from this study is the direct correlation between the porosity of SWMPCs and their permeability. As porosity increased, a marked improvement in permeability was observed, highlighting the material’s potential in applications where fluid flow is crucial. Furthermore, the mechanical properties of the composites were significantly influenced by the sintering temperature, with higher temperatures yielding superior bonding quality and, consequently, enhanced tensile properties. This underscores the importance of sintering conditions in optimizing the performance of SWMPCs.
The experimental investigation also shed light on the impact of the gap of the roller on the porosity and mechanical properties of the composites. A larger gap resulted in higher porosity but compromised mechanical strength, emphasizing the need for precision in the rolling process to achieve the desired balance between porosity and mechanical integrity. Additionally, the gap of the powder box emerged as a critical factor, with a wider gap leading to reduced porosity and improved tensile properties, further illustrating the nuanced effects of preparation parameters on the composite’s characteristics.
Remarkably, the study found that the number of folding layers had no significant impact on the porosity of the plates, which was primarily determined by the initial porosity of the thin strip. However, an increase in the number of layers enhanced the mechanical properties of the samples, suggesting that additional layers of wire mesh serve as reinforcement, improving the material’s resistance to deformation and fracture under tensile stress.
In conclusion, this research elucidates the complex interplay between the fabrication parameters and the resulting properties of SWMPCs, offering valuable guidelines for the design and optimization of porous metal composites. The findings highlight the potential of these materials in diverse applications, from filtration systems to structural components, where their unique combination of permeability and mechanical strength can be leveraged. As we advance, the insights gained from this study will undoubtedly inspire further exploration and innovation in the development of porous metal materials, contributing to the advancement of material science and engineering.
