Ultra-high Modulus Research Articles

Melt‐quenched oxide glasses with ultrahigh Young's modulus and small thermal expansion coefficient

AbstractThe well‐known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta2O5 contents in an MgO–Ta2O5–Al2O3–SiO2–B2O3 glass system using a conventional melt‐quenching method are revealed. The essential oxides of Al2O3 and Ta2O5 are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al2O3/[MgO + CaO] > 1). A small CTE is realized by increasing the molar ratio of Al2O3/MgO. According to magic‐angle spinning‐nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation.

Ultrahigh strength and modulus of polyimide-carbon nanotube based carbon and graphitic fibers with superior electrical and thermal conductivities for advanced composite applications

Development of carbon fibers (CFs) with high strength and high modulus for structural applications in CF-reinforced polymer (CFRP) industry has been a challenge. Herein, we propose a method for manufacturing highly oriented polymer–carbon nanotube (CNT) composite fibers having high strength (4.8 ± 0.2 GPa), modulus (390 ± 48 GPa), and electrical conductivity (5.75 ± 0.84 MS m-1) by a liquid crystalline wet-spinning process. The use of chlorosulfonic acid (CSA) as a solvent for CNTs and polyimide (PI) promotes dispersion and enables the production of high-performance composite fibers. In addition, the functional groups of PI in composite fibers improve the interfacial shear strength with epoxy resin without sizing additives by 72% compared to that of CNT fibers. Carbonization and graphitization of the composite fibers with an optimal ratio of PI (30%) and CNT cause significant improvement in their mechanical (tensile strength; 6.21 ± 0.3 GPa and modulus; 701 ± 47 GPa) and thermal properties (496 ± 38 W m−1 K−1) by reducing voids and improving orientation. We believe that the polymer–CNT composites and their CFs with high strength and high modulus would be the next-generation CFs for aerospace and defense industry.

Engineering DNA-Guided Hydroxyapatite Bulk Materials with High Stiffness and Outstanding Antimicrobial Ability for Dental Inlay Applications.

Programmable base pair interactions at the nanoscale make DNA an attractive scaffold for forming hydroxyapatite (HAP) nanostructures. However, engineering macroscale HAP mineralization guided by DNA molecules remains challenging. To overcome this issue, a facile strategy is developed for the fabrication of ultrastiff DNA-HAP bulk composites. The electrostatic complexation of DNA and a surfactant with a quaternary ammonium salt group enables the formation of long-range ordered scaffolds using electrospinning. The growth of 1D and 2D HAP minerals is thus realized by this DNA template at a macroscale. Remarkably, the as-prepared DNA-HAP composites exhibit an ultrahigh Young's modulus of ≈25GPa, which is comparable to natural HAP and superior to most artificial mineralized composites. Furthermore, anew type of dental inlay with outstanding antibacterial properties is developed using the stiff DNA-HAP. The encapsulated quaternary ammonium group within the dense HAP endows the composite with long-lasting and local antibacterial activity. Therefore, this new type of super-stiff biomaterial holds great potential for oral prosthetic applications.

Modelling and Analysis of CNC Milling Machine Bed with UHM CFRP composite Material

Abstract: Structural materials are used in a machine tool have a key role in defining the productivity, accuracy and Size proportions of the part manufactured by machine tool. The conventional structural materials like cast iron and Stainless or carbon steel at high operating speeds but used in precision machine tools grow positional errors due to the vibrations transferred into the Machine tool structure. Faster cutting speeds can be achieve only by structure which has good damping characteristics and high stiffness. Clearly the life of a machine tool is proportional to the levels of vibration Produce by machine. The further Work is carried out to Study the deformation and natural frequency using Static analysis and Modal analysis respectively. The bed in machine tool Took Major role in the precision in components. It is one of the greatest vital tool structures which is absorb the vibrations resultant from the cutting operation. To analyse the bed for possible material changes and Structure changes that could increase stiffness, decrease weight, expand damping characteristics and segregate natural frequency at the operating range. So main enthusiasm behind the impression to go for a composite Material in model involving ultra-High Modulus Carbon Fibre Reinforced Polymer Composite Material (UHM CFRP). In a carbon has good stiffness and strength properties but its absences in damping requirements. On the other hand, polymers, though its deficiencies in strength but, good damping in characteristics and it is easily holding the carbon fibres. So, this is makes greatest combination of materials in an appropriate manner. In this work, a machine tool’s bed is selected for the analysis static loads. Then study is carried out to decrease the weight of the machine tool’s bed without affecting its structural rigidity. The 3D CAD model of the bed has been created by using commercial 3D modelling software and analyses were carried out using ANSYS 2021 R2. Keywords: Composite material, hybrid structures, Milling machine bed, UHM CFRP.

Novel atomic-scale graphene metamaterials with broadband electromagnetic wave absorption and ultra-high elastic modulus

The weak visible-infrared broadband electromagnetic absorption, absence of bandgap, and low out-of-plane Young's modulus in graphene are three long-standing challenges plaguing its applications in optoelectronic and photonic devices. Herein, we propose a novel atomic-scale graphene metamaterial via vertically crossing graphene nanosheets, showing remarkable energetical, dynamical, and mechanical stability from state-of-the-art theoretical calculations. Compared with the zero bandgaps in pristine graphene, our graphene metamaterial exhibits a gap of 107 meV. Using pressure engineering, a tunable bandgap in the range of 0–260 meV was obtained, enabling our graphene metamaterial huge potential in semiconductor-based modern electronic devices. Anisotropic Young's moduli of over 1 TPa along the [010] direction and 413 GPa along the [001] direction were demonstrated. The in-plane Young's modulus (1085 GPa) is higher than that of the state-of-the-art technical ceramics such as SiC (about 425 GPa), Al2O3 (about 400 GPa), and Si3N4 (about 300 GPa), and the out-of-plane Young's modulus (413 GPa) is significantly increased comparing with monolayer graphene (about 2 GPa). Significant enhancement of broadband electromagnetic absorption for the visible (400–800 nm) and infrared light (1–6 μm) was achieved with a value of 50–1000 times higher than that of monolayer graphene, which promises the present graphene metamaterial a potential building block for photonic and optoelectronic devices.

Ultrahigh strength, modulus, and conductivity of graphitic fibers by macromolecular coalescence.

Theoretical considerations suggest that the strength of carbon nanotube (CNT) fibers be exceptional; however, their mechanical performance values are much lower than the theoretical values. To achieve macroscopic fibers with ultrahigh performance, we developed a method to form multidimensional nanostructures by coalescence of individual nanotubes. The highly aligned wet-spun fibers of single- or double-walled nanotube bundles were graphitized to induce nanotube collapse and multi-inner walled structures. These advanced nanostructures formed a network of interconnected, close-packed graphitic domains. Their near-perfect alignment and high longitudinal crystallinity that increased the shear strength between CNTs while retaining notable flexibility. The resulting fibers have an exceptional combination of high tensile strength (6.57 GPa), modulus (629 GPa), thermal conductivity (482 W/m·K), and electrical conductivity (2.2 MS/m), thereby overcoming the limits associated with conventional synthetic fibers.

Thermal Analysis of PE Extended Chain Crystal of PE Extended Chain Crystal from Gel Spinning

Abstract It has been recognized that ultra-high strength and high modulus ultra-highly drawn Polyethylene (PE) fiber is produced from the formation of extended chain crystal. Nevertheless, whether extended chain crystal exists in gel spinning ultra-highly drawn PE fiber is still an unsettled question. In this work, decalin was adopted as a solvent for PE gel spinning. By means of thermal analysis, X-ray diffraction methods etc, the existence of extended chain crystal was explored. Reasons for confusion in previous studies of this problem were discussed. In PE fiber from 3 wt-°/o dope, extended chain crystal starts to form during draw ratios over 20. When draw ratio equals 42, the content of extended chain crystal roughly equals that of folded chain crystal. The melting point of extended chain crystal is 6°C higher than that of folded chain crystal. They are 145.5° C and 150° C to 152.5° C respectively. The latter would slightly rise with arise of draw ratio. Multi-crystallization behavior of annealed PE fiber was determined and discussed. It was also confirmed that there is a linear logarithm relationship between thermal shrinkage (internal stresses) and fiber moduli.

Insight into Superior Electrochemical Performance of 4.5 V High-Voltage LiCoO2 Using a Robust Polyacrylonitrile Binder

The polyvinylidene fluoride (PVdF) binder is the classic binder for cathodes because of its excellent electrochemical stability and superior adhesion property. However, PVdF is very expensive and sensitive to moisture. Therefore, pursuit of a cost-effective binder is highly desirable, especially for high-voltage cathode application. Polyacrylonitrile (PAN) possesses strong polar C≡N groups, endowing it with oxidation resistance and strong binding properties. Herein, the PAN binder was systematically investigated for the electrochemical performance of the 4.5 V high-voltage LiCoO2 (HV-LCO) electrode. The results showed that the HV-LCO-PAN electrode delivered superior rate capability and cycling stability to the corresponding HV-LCO-PVdF. The PAN binder was highly tolerant of moisture and was capable of forming uniform coating on the cathode materials. Moreover, the PAN binder had ultrahigh mechanical modulus (8.01 GPa) and hardness (381.45 MPa) in a liquid electrolyte, thereby improving cycling stability and rate capability. X-ray photoelectron spectroscopy analysis further demonstrated that PAN formed uniform coating on the surface of LiCoO2 and played a role of an artificial cathode–electrolyte interphase layer, suppressing decomposition of the liquid electrolyte under high cutoff voltage.

Ductility and Stiffness of Laminated Veneer Lumber Beams Strengthened with Fibrous Composites

The paper presents the results of experimental research on unstrengthened and strengthened laminated veneer beams subjected to 4-point bending. Aramid, glass and carbon sheets with high tensile strength (HS) and ultra-high modulus of elasticity (UHM) glued to external surfaces with an epoxy resin adhesive were used as reinforcement. Two reinforcement layouts were used: (1) sheets glued along the bottom surface and (2) sheets glued to the bottom and side surfaces. Based on the test results, the flexural strength, flexural ductility and stiffness were estimated. Compared to the reference beams, the maximum bending moment was higher by 15%, 20%, 30% and by 16%, 22% and 35% for the Aramid Fiber Reinforced Polymers (AFRP), Glass Fiber Reinforced Polymers (GFRP) and Carbon Fiber Reinforced Polymers (CFRP) HS sheets, respectively. There was no significant increase in the flexural bending capacity for beams reinforced with UHM CFRP sheets. Similar values of bending ductility indices based on deflection and energy absorption were obtained. Higher increases in ductility were observed for AFRP, GFRP and CFRP HS sheets in “U” reinforcement layout. The average increase in bending stiffness coefficient ranged from 8% for AFRP sheets to 33% for UHM CFRP sheets compared to the reference beams.

Super-insulated, flexible, and high resilient mullite fiber reinforced silica aerogel composites by interfacial modification with nanoscale mullite whisker

Fiber-reinforced aerogel composites are extensively used in thermal insulation and energy-saving fields, while the inherently weak interface combination between fiber and aerogel undermines the effect of fiber reinforcement . To deal with this problem, mullite whiskers were in-situ synthesized on the surface of alumina silicate fiber through a facile and environmentally benign method. The nanoscale mullite whiskers growing on the fiber strengthen the interfacial bonding , thereby improving the mechanical properties of the composite. The alumina silicate fiber/mullite whisker/silica aerogel composites delivered ultrahigh compression stress and modulus of 6.45 MPa and 69.74 MPa at 50% strain, which is 6.14 times and 9.07 times higher than those of bare fiber reinforced silica aerogel . Meanwhile, the composite maintained a high retention rate of maximum stress of 97.8% after being compressed at 30% strain for 200 cycles. Moreover, the composite exhibits an ultralow thermal conductivity of 27.5 mW m −1 K −1 and a low density of 0.26 g cm −3 . The strong, resilient, lightweight composite with ultralow thermal conductivity is applicable for heat preservation and energy saving. • Mullite nanowhiskers were in-situ synthesized on alumina silicate fiber without F catalysts contaminating environment. • The stress (6.45 MPa) and modulus (69.74 MPa) at 50% strain increased dramatically due to interfacial enhancement. • The tough and resilient composite can be compressed at 30% strain for 200 cycles. • The composite also exhibited a low density (0.26 g cm −3 ) and a low thermal conductivity (27.5 mW m −1 K −1 ).

A simple and green strategy for preparing flexible thermoplastic polyimide foams with exceptional mechanical, thermal-insulating properties, and temperature resistance for high-temperature lightweight composite sandwich structures

Polyimide (PI) foams possess excellent mechanical properties, high-temperature resistance, and other unique properties, which facilitate impact in aerospace, automotive, and microelectronics industries. However, when they are used as lightweight insulation structural layers for high-temperature carbon fiber reinforced composites, improvement in thermal-insulating properties and temperature resistance of PI foams without compromising the flexibility in extreme environments is a challenging task. In this study, the flexible blocks were linked into rigid polymeric structures to fabricate a thermoplastic structure through a simple aqueous strategy to construct hydrogen-bonding networks. Thus, with a low shrinkage of 8.42%, an ultrahigh compressive modulus of 11.17 MPa, and a specific modulus of 81.03 MPa cm3 g−1 was successfully achieved. Benefitting from the formation of ultra-strong network backbones, foams showed excellent thermal-insulating properties and temperature resistance. The robust porous material with thermal-insulating properties (0.0481 W m−1 K−1) exhibited a compression modulus of 4.21 MPa after heat treatment at 300 °C and maintained 91% strength retention, thus it can be used as lightweight heat-insulation composite sandwich structures up to 300 °C. The copolymer foam obtained by using 30 mol% flexible blocks reserves its high flexibility undergoing only 10% dimensional changes after 40,000 compression-release cycles. The lightweight thermoplastic PI foams with flexibility, thermal-insulating properties, and temperature resistance can be used for high-temperature lightweight composite sandwich structures in aeronautics and space exploration.

Unraveling the Ultrahigh Modulus of Resilience of Core-Shell SU-8 Nanocomposite Nanopillars Fabricated by Vapor-Phase Infiltration

Unraveling the Ultrahigh Modulus of Resilience of Core-Shell SU-8 Nanocomposite Nanopillars Fabricated by Vapor-Phase Infiltration

Rivet-Inspired Modification of Carbon Nanotubes by In Situ-Reduced Ag Nanoparticles To Enhance the Strength and Ductility of Zn Implants.

Zinc shows promise for bone repair applications, while its strength and ductility require to be improved. Carbon nanotubes (CNTs) are exceptional reinforcements due to their superior strength, ultrahigh Young's modulus, and large aspect ratio. However, their strong agglomeration and weak interfacial bonding with the matrix are key bottleneck problems restricting the reinforcing effect. In this study, Ag nanoparticles were in situ reduced on CNTs and then the CNT@Ag powders were used to prepare Zn-CNT@Ag implants by laser powder bed fusion. Results showed that Ag reacted with Zn to form a "knot"-like AgZn3 phase. It had the same lattice structure (HCP) with Zn, which indicated a good lattice matching with the matrix, thus improving the dispersion of CNTs. More significantly, the knot played a "rivet" role and enhanced the load transfer capacity, which advantaged the CNT strengthening effects by assisting in transferring the load. Moreover, it enhanced the heterogeneous nucleation effects during solidification, which weakened the texture strength of the matrix and thus increased the ductility by improving the sliding capacity. The compressive yield strength, ultimate tensile strength, and elongation of the Zn-CNT@Ag implant were increased by 22, 26, and 17% in comparison to Zn-CNTs. Moreover, the Zn-CNT@Ag implant exhibited favorable antibacterial activity with a bacterial inhibition rate of 87.79%. Additionally, it also exhibited a suitable degradation rate and acceptable biocompatibility.

Fully biomass-based aerogels with ultrahigh mechanical modulus, enhanced flame retardancy, and great thermal insulation applications

Biomass-derived aerogels have received extensive attention as potential thermal management materials for energy-efficient buildings. However, it remains a huge challenge to fabricate a fully bio-based aerogel with excellent mechanical property, flame retardancy, and low thermal conductivity. Herein, we demonstrate a novel and facile strategy to manufacture a fully biomass-based aerogel from naturally abundant ammonium alginate (AL) and phytic acid (PA), in which PA acting as both flame retardant and cross-linking components constructs a strong network with AL matrix. Consequently, the resultant biomass aerogel with a low density of 0.052 g/cm 3 exhibits ultrahigh mechanical modulus (25.1 ± 3.1 MPa) and specific modulus (440.4 ± 54.4 MPa cm 3 ·g −1 ), much superior to those of biomass aerogels ever reported. Due to the existence of the uniform three-dimensional porous network, the biomass aerogels exhibit low thermal conductivity (34–38 mW/m·K) and excellent thermal insulation performances. Further, the introduction of PA endows the aerogel with high flame retardancy (limiting oxygen index value of 57%, UL-94 V-0 rating, and extremely low heat release), while the biodegradability of the materials keeps at a high level with a biodegradation rate of 91.43%. Combining with the advantages of mechanically strong property, high flame retardancy, excellent thermal insulation, and biodegradation, the aerogel of this work provides a new strategy to fabricate thermal insulation materials with high environmental safety.

Pseudoelasticity of SrNi2P2 Micropillar via Double Lattice Collapse and Expansion.

The maximum recoverable strain of most crystalline solids is less than 1% because plastic deformation or fracture usually occurs at a small strain. In this work, we show that a SrNi2P2 micropillar exhibits pseudoelasticity with a large maximum recoverable strain of ∼14% under uniaxial compression via unique reversible structural transformation, double lattice collapse-expansion that is repeatable under cyclic loading. Its high yield strength (∼3.8 ± 0.5 GPa) and large maximum recoverable strain bring out the ultrahigh modulus of resilience (∼146 ± 19 MJ/m3), a few orders of magnitude higher than that of most engineering materials. The double lattice collapse-expansion mechanism shows stress-strain behaviors similar to that of conventional shape-memory alloys, such as hysteresis and thermo-mechanical actuation, even though the structural changes involved are completely different. Our work suggests that the discovery of a new class of high-performance ThCr2Si2-structured materials will open new research opportunities in the field of pseudoelasticity.

CFRP strengthening of butt-welded ultra-high strength steels under quasi-static tensile loading

Due to the softening at the heat-affected zone (HAZ) in ultra-high strength steels (UHSS), the mechanical properties can deteriorate depending on the steels’ grade, welding heat input, and its associated cooling rate. Hence, a design based on the properties of the base material (BM) may not be appropriate, and there is a need to retain the lost properties of the weldment. This study presents an effort to strengthen butt-welded UHSSs using ultra-high modulus (UHM) carbon fiber reinforced polymer (CFRP) plates. Although the rehabilitation and strengthening of steel structures using CFRPs have been available during the last two decades, they have not been used to strengthen higher grades of steel such as UHSSs. For this aim, a series of tensile tests were carried out on butt-welded UHSSs strengthened with adhesively bonded UHM CFRP plates on both sides of the weldment. Two welding processes, i.e. the gas metal arc welding (GMAW) and laser welding, were implemented separately to join the plates. Microhardness measurements and tensile tests were carried out for the experimental part, as well as finite element (FE) analysis of the joints. The results were also compared with other available methods, i.e. high-frequency mechanical impact (HFMI) treatment and TIG-dressing (tungsten inert gas) of the weld toe that are commonly used to increase the fatigue life of UHSS joints. It was found that CFRP strengthening can not only retain the lost properties of the weldment but can also increase the joint strength up to 32% compared to the BM, and a considerable 50% higher stiffness. In contrast, the other methods (HFMI and TIG-dressing) had no impact on the tensile characteristics of the weldments.

Computational study of mechanical stability and phonon properties of MXenes Mo2ScC2T2 (T = O and F): 2D materials

The structural, electronic, elastic, and phonon properties of pristine Mo2ScC2 and surface terminated Mo2ScC2T2 (T = O and F) were investigated by employing density functional theory calculations. Generalized gradient approximation was used to model exchange–correlation effects. The electronic band structure was calculated using both Perdew–Burke–Ernzerhof and Heyd–Scuseria–Ernzerhof functional and found that all considered materials are metallic. Elastic constants, Young's moduli, shear moduli, in-plane stiffnesses, and Poisson's ratios were tabulated and showed that pristine Mo2ScC2 and surface terminated Mo2ScC2T2 satisfy the mechanical stability criteria. Furthermore, Mo2ScC2O2 has been found to be a significant candidate for ultrasensitive sensors due to its ultrahigh Young's modulus. The absence of the imaginary line in phonon band structures confirms the dynamic stability of Mo2ScC2, Mo2ScC2O2, and Mo2ScC2F2. Furthermore, Debye temperatures, phonon group velocities, thermodynamic properties, and Grüneisen parameters were calculated for Mo2ScC2 and Mo2ScC2O2. Finally, it is understood that Mo2ScC2 and Mo2ScC2O2 are suitable candidates for applications that require low thermal conductivity.

Ultrahigh stiffness and anisotropic Dirac cones in BeN4 and MgN4 monolayers: a first-principles study

Beryllium polynitrides, (BeN4) is a novel layered material, which has been most recently fabricated under high pressure (Phys. Rev. Lett. 126 (2021), 175501). As a new class of two-dimensional (2D) materials, in this work, we conduct first-principles calculations to examine the stability and explore the electronic nature of MN4 (M = Be, Mg, Ir, Rh, Ni, Cu, Au, Pd, and Pt) monolayers. Acquired results confirm the dynamical and thermal stability of BeN4, MgN4, IrN4, PtN4, and RhN4 monolayers. Interestingly, BeN4 and MgN4 monolayers are found to show anisotropic Dirac cones in their electronic structure. Although PtN4 monolayer is predicted to be a narrow bandgap semiconductor, IrN4 and RhN4 monolayers are found to be metallic systems. We also elaborately explore the effects of the number of atomic layers on the electronic features of BeN4 nanosheets, which reveal highly appealing physics. Our results highlight that BeN4 nanosheet yield ultrahigh elastic modulus and mechanical strength, outperforming all other carbon-free 2D materials. Notably, RhN4 nanosheet is predicted to yield high capacities of 562, 450, and 900 mAh/g for Li, Na, and Ca ions storages, respectively. This study provides a comprehensive understanding of the intrinsic properties of MN4 nanosheets and highlights their outstanding physics.

Super-flexible polyimide nanofiber cross-linked polyimide aerogel membranes for high efficient flexible thermal protection

• Novel super-flexible PI nanofiber crosslinked PI aerogel membrane was prepared. • The crosslinked structure realized the transition from brittleness to flexibility. • The lightweight membranes exhibited ultra-low thermal conductivity of 0.0279 W/mK. • The membranes showed high-temperature resistance and ultrahigh tensile modulus. Experimental preparation of lightweight and highly flexible aerogels has been a longstanding challenge, which limits their practical application in flexible thermal protection. Here, polyimide (PI) nanofiber cross-linked polyimide aerogel membranes were designed to achieve high flexibility, strong mechanical properties, and highly efficient heat-insulated performance. By taking full advantage of the perfect chemical compatibility and robust interfacial bonding strength between PI nanofibers and PI aerogel molecular chains, the PI aerogel membranes achieved the significant transformation from brittleness to high flexibility. The results demonstrate the addition of PI nanofibers exhibits significant reinforcement and toughening effect. PI nanofiber cross-linked PI aerogel membranes possess low density of 0.168 g/cm 3 and low thermal conductivity of 0.0279 W/mK. Moreover, 20 wt% PI nanofiber cross-linked PI aerogel membranes exhibit high tensile strength of 2.95 MPa, while the tensile strength of pure PI aerogel is 0.27 MPa. The as-prepared PI aerogel membrane exhibited high-temperature flexible thermal protection performance, which made it a candidate for the application in modern technology, military, and aerospace.

Growth of diamond coating on carbon fiber: Relationship between fiber microstructure and stability in hydrogen plasma

Stability of carbon fiber in hydrogen plasma during chemical vapor deposition growth of diamond film was investigated for a range of carbon fiber samples with different physical properties. Morphological studies using scanning electron microscopy and focused ion beam showed that pre-growth seeding with nanodiamonds was necessary both to protect the carbon fiber from atomic hydrogen attack and to promote diamond growth. Microstructural studies using Raman spectroscopy indicated that carbon fibers with larger crystallite size, which correspond to high and ultra-high modulus fibers, were less susceptible to etching compared to carbon fibers with smaller crystallite size, corresponding to intermediate modulus fibers. A model was developed to predict the diamond film coverage, following pre-seeding of the carbon fibers with nanodiamonds. Compared to larger seeds, a dense seeding with smaller sized nanodiamonds resulted in faster coalescence, which provides significant benefits as the diamond layer protects the carbon fiber from hydrogen plasma attack. The results of this study will facilitate the integration of diamond and carbon fiber into a versatile hybrid material and, in particular, pave the way towards development of novel biocompatible diamond-coated carbon fiber micro-electrodes with long-term efficacy.