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MAX phase materials

MAX phase materials are hexagonal ternary carbides or nitrides with structures of nanolayers, that provide a unique and interesting combination of both metallic and ceramic properties.

MAX phase materials exhibit high stiffness, easy machinability, super ductility and importantly have an impressive ductile-to-brittle transition temperature ranging from 825 to 1950 °C. Apart from the above mentioned attractive characteristics, MAX phase materials also demonstrate excellent resistance to aggressive machining medium and high thermal and electrical conductivity, which makes easier to use it as biosensor drill applications.

Unit cells of the Mn+1AXn phases PVD

Unit cells of the Mn+1AXn phases for (a) n = 1 or M2AX, (b) n = 2 or M3AX2, and (c) n = 3 or M4AX3 phases

Figure Curtesy: Annual Review of Materials Research 41(1):195-227

However, what makes the material more attractive to me is, the process which makes the excellent quality MAX phase materials. Physical Vapor Deposition (PVD) is the best way to produce high quality Cr2AlC MAX phase material, and we, AVALUXE supply high quality targets AlCr targets and metal doped carbon targets with excellent HiPIMS recipes for such processes.

We are excited to share our experimental studies with High Power Impulse Magnetron Sputtering (HiPIMS) process used to deposit MAX phase Cr2AlC material, as it has shown an excellent resistance to high-temperature oxidation in air due to the formation of a continuous, dense, and adherent alumina scale layers during the machining process. Nevertheless the diffusion and oxidation of aluminum in the material in cracks also result in self-healing properties and thermal-shock resilience to the overall coating layer system.

Comparison   of theoretical and experimental values of bulk and Young's modulus E Figure PVD

Comparison of theoretical and experimental values of bulk and Young's modulus E Figure

Curtesy: Annual Review of Materials Research 41(1):195-227

Our customers in Proton exchange membrane (PEM) fuel cells, aircraft industries and tool coatings have a great reason to cheer that we are involving in the development of MAX phase coatings for other applications and obtain very impressive outcomes.

Our early results shown that a substantial improvement has been observed with the corrosion resistance property of steel bipolar plates in fuel cells. Cr2AlC coatings are also suitable for the corrosion resistance property in the materials used in aircraft turbines. A promising results has been obtained in an attempt to increase the lifetime and operating temperature of thermal barrier coatings and to protect turbine blades from erosion.

Why HiPIMS technology is very crucial in the development and synthesis of MAX phase materials ? Let me tell you about this.

The transformation of Cr-Al-C system from its amorphous phase to the polycrystalline Cr2AlC MAX phase is a crucial part of MAX phase material synthesis process. Such solid phase transformation from its amorphous to polycrystalline Cr2AlC MAX phase of material happens in two subsequent steps.

In the first step of the process, solid-state diffusion facilitates the formation of a disordered CrAlC solid solution. In the next step, localized reorganization mechanism of the solid solutes takes place, which drives the conversion of disordered amorphous state to ordered Cr2AlC MAX phase. An important thermal activation is indeed required to promote elemental diffusion and surface mobility over important distances inducing the growth of highly ordered MAX phases.

HiPIMS ability to generate high ionization and facilitating energetic impact of depositing ions into the growing surface provide excellent elemental diffusion and surface mobility, and thus produces excellent Cr2AlC MAX phase materials.


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