Nanodiamond Composites Research Articles

Wear-resistant and stable low-friction nanodiamond composite superhard coatings against Al2O3 counter-body in dry condition

Conventional machining lubricants pose environmental hazards and increase production costs. This study addresses this challenge by investigating nanodiamond composite (NDC) coatings deposited on WC–Co substrates as a lubricant-free alternative for sustainable machining. The NDC films show superior hardness (65 GPa) compared to the substrate (22 GPa) and enhanced adhesion (HF2). The NDC's unique self-lubrication results in a low and stable friction coefficient (COF ≤ 0.095) and exceptional wear resistance (7.45 × 10−8 mm3/N·m) in dry tesing against Al2O3 counter-body. Compared to CVD diamond, NDC coatings show a 47.8 % reduction in COF and a 31.65 % enhancement in wear resistance, promoting environmentally friendly machining practices.

Nanomechanical and Structural Characteristics of Nanodiamond Composite Films Dependent on Target-Substrate Distance

AbstractThis study explores the optimization of target-substrate distance (TSD) in coaxial arc plasma deposition technique for depositing nanodiamond composite (NDC) films on unheated WC–Co substrates, with a focus on enhancing properties relevant to cutting tool applications. TSD significantly impacted film growth and adhesion, while hardness and Young’s modulus remained stable within the 10–50 mm TSD range. Increased TSD led to reduced deposition rates and film thickness, but improved quality by eliminating macroparticles and reducing surface roughness. Notably, the NDC film deposited at 10 mm TSD exhibited exceptional adhesion resistance, a thickness of 11.45 μm, low compressive internal stress (2.8 GPa), and a surface roughness (Sa) of 280 nm, coupled with an impressive hardness of 49.12 GPa. This film also achieved a favorable deposition rate of 1.05 nm/s. In comparison, the film deposited at 15 mm TSD displayed a maximum hardness of 51.3 GPa, lower Sa of 179 nm, but a reduced deposition rate of 0.29 nm/s. The estimated C sp3 fraction correlated well with the nanoindentation measurements, while internal stress showed a consistent relationship with film adhesion. These findings suggest that a TSD of 10 mm is optimal for balancing hardness, adhesion, deposition rate, and surface roughness, making NDC films a promising candidate for cutting tool applications.

Unveiling a 72.5 GPa peak hardness in sustainable nanodiamond composite hard coatings via discharge energy control: A nanoindentation-Raman approach

Sustainable nanodiamond composite (NDC) films hold promise for high-performance hard coatings thanks to coaxial arc plasma deposition (CAPD). This eco-friendly technique eliminates the need for external heating, chemical reactions, or Co substrate pre-treatment. CAPD boasts lower energy consumption and faster deposition rates, making it a sustainable solution for the growing demand for high-quality, environmentally friendly coatings. This study investigates the influence of discharge energy on the nanostructure and mechanical properties of these NDC films. Optimal discharge energy, ranging from 2.3 to 12 J/pulse, was meticulously explored. A combined nanoindentation-Raman approach reveals a significant correlation between discharge energy and film properties. Remarkably, at 7 J/pulse, a peak hardness of 72.5 GPa is achieved, surpassing other energy levels. Raman spectroscopy confirms maximum nanodiamond content at this energy level (evidenced by maximized Adia/AG ratio, indicating a higher diamond-to-graphite ratio), along with minimal graphitization. Additionally, the presence of trans-polyacetylene (t-PA) peaks (denoted as At-PA) revealed the existence of maximum grain boundaries ratio (At-PA/AG), contributing to enhanced mechanical properties. Optimizing discharge energy tailors NDC film nanostructure, enhancing mechanical performance for advanced hard coatings.

Wear-resistant and adherent nanodiamond composite thin film for durable and sustainable silicon carbide mechanical seals

In response to environmental concerns, there is a growing demand for durable and sustainable mechanical seals, particularly in high-risk industries like chemical, petroleum, and nuclear sectors. This work proposes augmenting the durability and sustainability of silicon carbide (SiC) ceramic seals with the application of a nanodiamond composite (NDC) film through coaxial arc plasma deposition (CAPD) in a vacuum atmosphere. The NDC coating, with a smooth surface roughness of Ra = 60 nm as substrate, demonstrated a thickness of 1.1 μm at a deposition rate of 2.6 μm/h. NDC film has demonstrated exceptional mechanical and tribological characteristics, such as a hardness (H) of 48.5 GPa, Young's modulus (E) of 496.7 GPa, plasticity index (H/E) of 0.098, and fracture toughness of H3/E2 = 0.46 GPa, respectively. These NDC films showcased commendable adhesion strength (>60 N), negligible wear, and low friction (≤0.18) during dry sliding against a SiC counter material. Raman analysis has confirmed the nanocomposite structure of NDC film, emphasizing the role of highly energetic carbon ions in enhancing film adhesion by forming SiC intermetallic compounds at the interface through the diffusion of silicon atoms from the substrate into the films. The abundance of grain boundaries and rehybridization of carbon sp3 to sp2 bonding is perceived to improve tribological performance. CAPD excels in synthesizing long-life eco-friendly NDC coatings for durable and sustainable mechanical seals, featuring smooth surfaces, superior adhesion, outstanding hardness, and wear resistance, making them high potential candidates for various tribological applications.

Structure and properties of self-assembled graphene oxide–detonation nanodiamond composites

The properties of graphene oxide–detonation nanodiamond composites obtained as a result of heterocoagulation of graphene oxide and hydrogenated detonation nanodiamonds in aqueous mixtures were studied. The resulting composites with different proportions of graphene oxide and detonation nanodiamond were subjected to drying and subsequent heat treatment in a vacuum, converting graphene oxide into graphene. The structure of the composites was studied using electron microscopy and Raman spectroscopy. The specific surface area and porosity of the obtained samples were studied by analyzing nitrogen adsorption isotherms. A model for the composite formation and a possible technology for producing a material based on it with different specific surface area values and pore structure are proposed. It is shown, that the largest possible specific surface area of two-component structures of the «DND/GO» type does not exceed 500 m2·g−1. It was also concluded that it is necessary to achieve a uniform distribution of detonation nanodiamond particles over the surface of graphene sheets.

Sustainable super-hard and thick nanodiamond composite film deposited on cemented carbide substrates with an interfacial Al-interlayer

Super-hard nanodiamond composite (NDC) films, synthesized via cathodic arc plasma deposition on unheated WC − Co substrates, offer an eco-friendly solution for cutting tools. A 100 nm-thick Al-interlayer mitigates Co catalytic effects, improving adhesion and yielding smooth and dense 10 µm-thick films at a deposition rate of 3.3 μm/hr. These grain-boundary-rich nanostructured films, with an impressive 58 GPa hardness attributed to a substantial 70 % C sp3 fraction, prove optimal for hard coatings. The Al-interlayer effectively suppresses Co catalytic effects, forming a dense Al-oxide layer, enhancing film hardness and adhesion (Lcr = 18.6 N). NDC films present a promising eco-friendly option for high-performance hard coatings.

Revealing mechanical and structural properties of Si-doped nanodiamond composite films through applied biasing voltages on WC − Co substrates

Silicon-doped nanodiamond composite (Si-NDC) films hold significant promise for advancing cutting tool performance in demanding applications. These films, created through coaxial arc plasma deposition from 1 at.% silicon blended graphite targets, eliminate the need for external heating, chemical reactions, Co etching, or nanodiamond seeding on cemented carbide substrates. This study explores the influence of biasing voltages (0 V, −50 V, and − 100 V) during Si-NDC film deposition on their mechanical properties. As biasing voltage increased from 0 to −100 V, Si-NDC films displayed remarkable improvements in hardness (from 56 to 65 GPa) and Young's modulus (from 535 to 655 GPa). These enhancements stem from the presence of nanodiamonds, C − Si sp3 bonds, and unique features within the amorphous carbon matrix. Nevertheless, this transformation introduced higher internal stress levels (0.88 to 3.75 GPa), adversely affecting film-substrate adhesion, which decreased from a critical load of 31 N to 16.6 N for unbiased and − 100 V biased films, respectively. Intriguingly, unbiased films exhibited enhanced adhesion attributed to the formation of intermetallic compounds like CoSi2 and SiC. Surface roughness increased from 90 nm to 180 nm with −100 V biasing, attributed to droplet attraction. Biasing improved film hardness but aggravated internal stress, impacting adhesion and surface roughness.

Influence of the Sign of the Zeta Potential of Nanodiamond Particles on the Morphology of Graphene-detonation Nanodiamond Composites in the form of Suspensions and Aerogels

Influence of the Sign of the Zeta Potential of Nanodiamond Particles on the Morphology of Graphene-detonation Nanodiamond Composites in the form of Suspensions and Aerogels

Synthesis and comprehensive synchrotron-based structural analysis of Si-doped nanodiamond composite films deposited on cemented carbide

Si-doped nanodiamond composite (NDC) films were deposited on unheated WC − Co substrates by coaxial arc plasma deposition for advanced cutting tools applications. The nanoindentation test revealed changes in films hardness and Young's modulus attributed to various Si doping concentrations (0, 1, 5, and 20 at.%) and the catalytic effects of Co diffused from the substrate surface into the films. To reveal the physical origin behind these changes, the films' structure was examined by synchrotron-based Auger electron spectroscopy (AES), soft X-ray photoemission spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). The AES and XPS analysis showed a consistent correlation between nanoindentation measurements and the estimated C sp3 fraction in the films. The NEXAFS spectra revealed intense C − C σ* resonance, consistent with the measured film hardness. The 1 at.% Si-doped film, deposited with an undoped NDC buffer layer to mitigate the Co catalytic effects, exhibited the highest hardness of 60 GPa, the largest C sp3 fraction, and the most intense CC σ* peak. Si doping resulted in the formation of C − Si sp3 bonds at the expense of C sp2 bonds, increasing the fraction of C sp3 bonds and enhancing film hardness. The synchrotron-based analysis effectively revealed the electronic states of NDC hard coatings, particularly after the removal of surface contaminants through mechanical polishing.

Influence of different pretreatments on the adhesion of nanodiamond composite films on Ti substrates via coaxial arc plasma deposition

In this study, we report on the novel growth of nanodiamond composite (NDC) films on titanium (Ti) substrates using the coaxial arc plasma deposition (CAPD) at room temperature, which offers several advantages over conventional growth techniques. CAPD employs a unique coaxial arc plasma gun structure that provides a supersaturated condition of highly energetic carbon ions (C+) for ultrafast quenching on the substrate, promoting the growth of nanodiamond grains. This allows for NDC films’ growth on diverse substrates without the need for initial seeding or substrate heating. However, the growth of NDC films on Ti substrates at room temperature is challenging due to the native oxide layer (TiO2). Here, we grew NDC films on Ti substrates using three different pretreatments: (i) hydrofluoric acid (HF) etching, (ii) insertion of a titanium carbide (TiC) intermediate layer, and (iii) in situ Ar+ plasma etching. The morphology and structure of the grown NDC films were examined by 3D laser, high-resolution scanning electron microscopies (HR-SEM), Raman, and x-ray photoelectron (XPS) spectroscopies. Our results demonstrate that in situ Ar+ plasma etching is the most effective pretreatment method for completely removing the native TiO2 layer compared to the other two ex situ pretreatments, in which re-oxidation is more likely to occur after these pretreatments. Furthermore, NDC films grown using the hybrid Ar+ ion etching gun (IG) and CAPD exhibit the highest sp 3 content (63%) and adhesion strength (16 N).

B-doped nanodiamond composite hard coatings deposited on cemented carbide: Mechanical, structural, and tribological properties

Herein, the effects of B doping on the mechanical, structural, and tribological properties of nanodiamond composite (NDC) coatings deposited on cemented tungsten carbide-based Co binder substrates via coaxial arc plasma deposition are studied. The results reveal decreasing films hardness 35, 27, and 25 GPa with increasing B contents of 1, 5, and 10 at.%, respectively, which is attributed to film graphitisation. Graphitisation is induced by the catalytic effects of Co atoms, which diffuse proportionally from the substrate surface into the films with increasing B content. However, Co diffusion hardly occurs during the deposition of undoped films. The 1 at.% B-doped films with an undoped NDC buffer layer exhibit enhanced hardness from 35 to 58.3 GPa owing to a decrease in the catalytic effects of Co, thereby resulting in the formation of a high amount of CC sp3 bonds at the expense of CC sp2 bonds. The adhesion of the doped films is improved by a factor of three compared with the undoped films owing to enhanced film hardness and toughness as B doping tends to release internal stress by forming long CB bonds. The sliding behaviour remains at a friction coefficient of approximately 0.08 owing to the presence of sacrificial B2O sliding layers and graphitic self-lubrication phases. The B-doped NDC films are promising hard coatings for machining difficult-to-cut materials.

Heat-conducting properties of thermobarically-sintered detonation nanodiamond

The research was conducted to study the thermal conductivity of detonation nanodiamonds-based composites. Composite nanodiamond materials were obtained in the course of thermobaric sintering at the press-free high-pressure apparatus (BARS) under 5 GPa and at temperatures within the range of 1100 –1500°С. It was ascertained that unlike diamond monocrystals with their thermal conductivity reaching up to 2100 W / (mK), the thermal conductivity of a nanodiamond composite is considerably lower and does not go beyond 18 W / (mK). Specifically, the temperature dependence of the thermal conductivity coefficient of a nanodiamond composite is anomalous as compared to a similar dependence in diamond monocrystals. The thermal conductivity coefficient in diamond monocrystals grows in compliance with the rising temperature, whereas it shows practically no changes in a nanodiamond composite in the temperature range of 50 – 300°С. Such a temperature dependence of the thermal-conductivity coefficient is apparently related to the features of the phonon spectrum of diamond monocrystals. This feature is stipulated by the dependence of the phonon spectrum of nanocrystals on their size, represented by a set of phonon modes in the range of the wave vector 0 < q <1 / L, i.e., the size of a diamond nanocrystal of 4.5 nm is alleged to limit the excitation of harmonics during nanodiamond composite heating, as opposed to macroscopic crystals that demonstrate the excitation of higher-frequency phonon modes during temperature growing.

Adhesion of nanodiamond composite films on Ti substrates at room temperature via hybrid ion etching gun and coaxial arc plasma deposition

It has been extremely difficult for nanodiamond composite (NDC) films to be deposited on Ti due to a large thermal expansion coefficient difference. The native oxide layer on Ti is another problem preventing the appropriate adhesion of NDC films and subsequent delamination. In this work, innovative room temperature adhesion of 3 μm NDC films with 54 GPa hardness on Ti substrates was accomplished via a hybrid system of ion etching gun and coaxial arc plasma deposition (CAPD). Ar+ plasma etching is capable to terminate the superficial TiO2 layer and manipulates substrate morphology during CAPD provides instantaneous deposition of NDC films at room temperature.

Characterization and tribology performance of polyaniline-coated nanodiamond lubricant additives

Abstract The polyaniline (PANi)-coated nanodiamond (ND) composites were fabricated by the in situ polymerization process and dispersed in base oil as nanolubricant additives by ultrasonic-assisted dispersion. The morphology and microstructures of the nanocomposites were characterized. The in-house developed reciprocating tribo-device was utilized to conduct the tribological tests. An actual CrN piston ring–nitriding cylinder liner friction pair used in the diesel engine was employed to evaluate the effectiveness of the developed nanolubricant additives. The wear tests were conducted under conditions that were close to the actual work condition of the selected friction pair. Furthermore, the anti-scuffing performance was also investigated and the associated mechanisms were analyzed. The results show the polymerization process inhibited the agglomeration of the NDs that were well dispersed in the PANi matrix. The stable hydrogen bonding interactions and the surface confinement effect promote the dispersion of the nanocomposites in organic base oil effectively. The developed additive can improve the friction and wear performance of the ring–cylinder liner friction pair by 12–19 and 15–24%, respectively, compared with the base oil. With the increase of temperature, the effectiveness of the nanolubricant additives is enhanced. Under the oil-starved condition, the friction pairs lubricated with PANi/ND lubricants can sustain a longer stable period with a lower friction force, and the anti-scuffing time is almost three times longer. Concerning the overall tribological performance, the optimal content of the PANi/ND additive in base oil is 2 wt%.

Nanodiamond composites: A new material for the preservation of parchment

AbstractIn this work, the application of nanodiamond (ND)‐composites and dispersions as consolidating agents for parchment substrates has been studied. Different nanocomposites and ND‐based dispersions have been tested showing very promising results and making ND a potential high‐performance additive in the field of restoration. The effect of ND treatment on parchment has been evaluated by analyzing the variations in the parchment denaturation temperature, with respect to the untreated samples, by means of the Light Transmission Analysis (LTA), before and after artificial aging. The hydrolysis/gelatinization degree of the collagen molecule has also been analyzed by means of the Attenuated Total Reflection Fourier Transform IR (FTIR‐ATR) spectroscopy on the same samples investigated by LTA. ND composites, at certain concentrations, seem to improve the structural stability of the collagen networking, contrasting the thermo‐hygrometrically induced aging. Therefore, ND has confirmed to be a promising material to be applied for the restoration and conservation of Cultural Heritage.

A brief review on synthesis and application of polymer–nanodiamond composite

Recent research and findings have drawn attention to the emergence of nano diamond-based polymer nanocomposites. The unique nanoscale carbon structural units known as nanodiamonds have a variety of exceptional mechanical, chemical, optical, and biological features that make them important andeffective species serving as carriers for technical and biomedical applications. To produce high-performance composites that may be employed in electrochemical energy storage devices, the nano diamond-polymer nanocomposites mitigate the different challenges that arise in the pursuit of high performance polymeric compounds. The focus of this review is on the fundamental characteristics, fabrication methods, surface engineering strategies, toxicity concerns, energy production and biomedical applications of composites made of polymers -nanodiamond composites.

Influence of the sign of the zeta potential of nanodiamond particles on the morphology of graphene-detonation nanodiamond composites in the form of suspensions and aerogels

A new method of using the detonation nanodiamond with positive and negative zeta potential as a spacer for aerogels based on graphene oxide is presented. It is shown that the dosed addition of detonation nanodiamonds' particles to the suspension of graphene oxide hydrosol made it possible to triple the specific surface area of the resulting aerogel compared to graphene oxide aerogel, and this effect is more significant when nanodiamonds with a positive zeta potential are used. It was also shown that aerogels derived from graphene oxide and detonation nanodiamond with a positive zeta potential have a specific morphology with graphene oxide platelets being twisted. This effect is discussed in terms of the change in the average zeta potential of the initial mixtures. Keywords: two-component systems, carbon materials, colloid chemistry.

Mixed sp2-sp3 Nanocarbon Materials: A Status Quo Review.

Carbon nanomaterials with a different character of the chemical bond—graphene (sp2) and nanodiamond (sp3)—are the building bricks for a new class of all-carbon hybrid nanomaterials, where the two different carbon networks with sp3 and sp2 hybridization coexist, interacting and even transforming into one another. The extraordinary physiochemical properties defined by the unique electronic band structure of the two border nanoallotropes ensure the immense application potential and versatility of these all-carbon nanomaterials. The review summarizes the status quo of sp2 – sp3 nanomaterials, including graphene/graphene-oxide—nanodiamond composites and hybrids, graphene/graphene-oxide—diamond heterojunctions, and other sp2–sp3 nanocarbon hybrids for sensing, electronic, and other emergent applications. Novel sp2–sp3 transitional nanocarbon phases and architectures are also discussed. Furthermore, the two-way sp2 (graphene) to sp3 (diamond surface and nanodiamond) transformations at the nanoscale, essential for innovative fabrication, and stability and chemical reactivity assessment are discussed based on extensive theoretical, computational and experimental studies.

Microstructure and Properties of Nickel/Detonated Nanodiamond Composites Fabricated by Powder Metallurgy

Abstract Nickel/detonated nanodiamond composites were prepared using the powder metallurgy technique. Detonated nanosized diamond particles were reinforced in the nickel matrix. The investigated powder was used to prepare homogenous diamond/nickel composite mixtures with different detonated nanodiamond content of weight percentage (0.2, 0.4, 0.6, and 0.8 wt.%). The produced mixtures were cold pressed into a cylindrical die shape under compaction pressure of 400 MPa followed by sintering at 1,000°C for 120 min under a controlled atmosphere of 1:3 hydrogen/nitrogen gas mixture. Phase identification and microstructure of the produced sintered samples were investigated using X-ray diffraction and scanning electron microscope, respectively. The results of the microstructure show a good distribution of the detonated nanodiamond in the nickel matrix, especially in the 0.8 wt% diamond/nickel sintered sample. The densities of the obtained sintered samples were measured by applying the Archimedes principal. As the detonated nanodiamond content was increased in the nickel matrix, the density of the sintered samples was decreased. The thermal expansion, electrical conductivity, and hardness of the produced diamond/nickel composites were measured. The coefficient of thermal expansion and electrical conductivity were decreased, but the hardness was increased by increasing the detonated nanodiamond weight percentage.

Functionalized nano diamond composites for photocatalytic hydrogen evolution and effective pollutant degradation

Development of superior heterogeneous photocatalyst for hydrogen (H2) evolution with promising pollutant degradable capacity is a significant feature but then again thought-provoking for shaping the energy and environmental issues. In this regard, a photocatalytic H2 evolution using nano diamond (ND) semiconducting materials having pollutant degradable capacity for Rhodamine B dye (RhB) has been rarely reported and hence predicted to the sustainable energy. Productive characteristics such good chemical stability, super hardness, nanometer size, biocompatibility and thermal conductivity, ND is a capable and highly valuable powder physical material. Non-uniform and agglomeration dispersion spread of ND in different solvents are the main problems preventing ND from the wide-use in commercial applications. Upon 535 nm solar light excitation, the fabricated ND sample exhibit remarkable photocatalytic H2 production with a HER of about 400 μmol h−1 than pristine ND (197 μmol h−1). Additionally, this H2 generation dramatically enhances the quantum yield, indicating the H2 terminated sites work as electron reservoirs. Precisely, the kinetic constant pseudo-order of FND for photodegradation of RhB was higher as compared with pristine ND. As such, the results show an important step toward tailor-designed and explain the vital role of FND composites for the rational motifs of fruitful photocatalyst with effective pollutant degradable capability for future demand.