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The hard part turning process used to finish the cylindrical surfaces has some critical machining responses like tool wear with the lower quality of the machined surfaces. Minimum quantity lubrication (MQL)-based machining environment is currently considered an advanced cooling and lubrication technique. Cutting speed, feed rate, and cutting depth are considered input parameters, and the TaguchiL₂₇ orthogonal array (OA) has been adopted as the design of the experiment. In this context, average surface roughness ($R_a$), tool flank wear (VBc), cutting temperature ($T^{\circ }$C), and chip morphology have been selected as measured outputs. To improve the machining performance of hardened steel, a sustainable MQL ($\mathrm{\text{flank}}+\mathrm{\text{rake}}$ directions) cooling system has been employed at the cutting zone. Iron–aluminum LRT 30 was considered as the base fluid for the hard turning of AISI 4340 steel by PVD (AlTiN) and CVD (TiN/TiCN/Al₂O₃) coating cutting inserts. The primary effects of process parameters and their influences on the measured outputs have been discussed. The dual jet MQL-based hard turning was performed at three levels of cutting speeds (80, 170, and 260m/min), feed rate (0.5, 0.1, and 0.15mm/rev), and cutting depth (0.2, 0.3, and 0.4mm) with an air pressure of 5bar and mist flow rate 50ml/h. The findings showed that PVD-coated carbide tools outperformed CVD-coated tools. The model of the measured outputs of both tools has been developed using second-order regression analysis. Utilizing ANOVA analysis, all the predictive models were observed to be significant and acceptable with larger than 90% of $R^2$ value.

Nanodiamonds (NDs) have unique optical and mechanical characteristics, surface chemistry, extensive surface area and biocompatibility, and they are nontoxic, rendering them suitable for a diverse range of applications. Recently, NDs have received significant attention in nano-biomedical engineering. This review discusses the recent advancement of NDs’ biomedical engineering, historical background, basic introduction to nanoparticles and development. We summarize NDs’ synthesis technique, properties and applications. Two methodologies are used in ND synthesis: bottom-up and top-down. We cover synthesis methods, including detonation, ball milling, laser ablation, chemical vapor deposition (CVD) and high pressure and high temperature (HPHT); discuss the properties of NDs, such as fluorescence and biocompatibility. Due to these properties, NDs have potential applications in biomedical engineering, including bioimaging, biosensing, drug delivery, tissue engineering and protein mimics. Further, it provides an outlook for future progress, development and application of NDs in biological and biomedical areas.

Graphene transistors using large area chemical-vapor-deposited (CVD) monolayer graphene and advanced dielectric stacks are constructed and examined. Top-gated devices with a SiO₂/Al₂O₃ gate-dielectric have a Dirac Point (DP) located at less than 5 V and asymmetric electron/hole mobility. In contrast, devices based on an advanced AlN interfacial layer have a DP located near 0V and a near symmetric carrier mobility- characteristics that could be more suitable for applications that require ambipolar behavior and low-power operation. For the first time, a measured RF cut-off frequency range of 1GHz is measured for top-gated transistors using CVD graphene. The results are of importance for the realization of graphene based, wafer-scale, high frequency electronics.

The electron drag effect of carbon nanotubes in electrolyte was studied. The carbon nanotubes in this study were synthesized by hot filament CVD. The experimental results showed there is a striking induced voltage on the surface of carbon nanotubes in flowing electrolytes. It was also found that the induced voltage was closely depended on the electrolyte concentration. The response time of induced voltage was relative to the kind and concentration of electrolytes. The origin of induced voltage was discussed.

The magneto resistive effect in nanocystalline diamond films was investigated at room temperature. The nanocystalline diamond films on silicon were deposited by hot filament chemical vapor deposition. The experimental results showed that a striking magneto resistive effect in p-type doped nanocystalline diamond films was observed. The relative changes in the resistivity of the films were about 0.3 at room temperature under the magnetic field of 5T, and increased with decreasing the geometrical size of the devices. It was found that the magneto resistive effect in the nanocystalline diamond films was less than that of epitaxial diamond films. This was ascribed to a large number of grain boundaries. The results are discussed in detail.

Here we used the iron oxide nanoparticles derived from ferritin as catalyst for the synthesis of carbon nanotubes (CNTs) by the chemical vapor deposition (CVD) of coal gas. It has been found that the structure and morphology of CNTs can be tailored, to some degree, by varying the experimental conditions such as catalyst loading and process parameters. In addition to straight CNTs, some Y-branched CNTs were also obtained, which might be due to the sulfur species in the coal gas.

The influence of methane gas (CH₄) pressure on the optical, electrical and structural properties of the nitrogenated amorphous carbon nitride (a-C:N) films grown by microwave surface wave plasma chemical vapor deposition (SWP-CVD) on quartz and silicon (100) substrates have been studied. The a-C:N films are deposited with varying CH₄ gas ranging from 5 to 20 ml/min. To incorporate nitrogen in the film, we have introduced nitrogen gas (N) at 5 ml/min in the chamber. The effects of CH₄ gas pressure on the surface morphology, composition, structure, and electrical properties of the N-incorporated camphoric carbon thin films have been investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), Auger electron spectroscopy (AES), UV-visible spectroscopy and four-probe resistance measurement. We have succeed in growing a-C:N thin films using SWP-CVD at room temperature and found that the amorphous structure of a-C films can be changed and is strongly dependent on the CH₄ gas source.

The n-type conductivity nitrogen-doped amorphous carbon (n-C) films have been grown by surface wave microwave chemical vapor deposition (SWP-CVD) on plastic and quartz substrates. The bonding, electrical and photovoltaic properties have been studied. The Tauc plot of UV-Visible measurement have shown that n-C films deposited on plastic have smaller optical band gaps compared to the films grown on quartz substrate at the same parameters. Temperature dependence and photoresponse measurements also have shown that the properties of n-C thin films deposited on plastic have higher photoelectrical response. Our experimental results have shown that the flexible polytetrafluoroethene plastic substrate is a reliable candidate for future photovoltaic applications.

A numerical study is needed to gain insight into the growth mechanism and improve the reactor design or optimize the deposition condition in chemical vapor deposition (CVD). In this study, we have performed a numerical analysis of the deposition of gallium arsenide (GaAs) from trimethyl gallium (TMG) and arsine in a vertical CVD reactor. The effects of operating parameters, such as the rotation velocity of susceptor, inlet velocity, and inlet TMG fraction, are investigated and presented. The three-dimensional model which is used in this investigation includes complete coupling between the thermal-fluid transport and species transport with chemical reaction.

We report the effect of a Cr layer on the glass substrate during the growth of carbon nanotubes (CNTs) by chemical vapor deposition. When Fe was used as a catalyst in the CNT growth, longer CNTs were obtained by increasing the thickness of the Cr layer. However, CNTs were not grown on the surface with a thick Cr film and Co or Ni catalyst. These results arise from a difference in the mechanism of CNT formation when using different catalyst metals.

Cu seed layer was deposited by chemical vapor deposition using new Cu precursor, Cu(dmamb)₂. The Cu layers still need the barrier layer to prevent the diffusion, so Ta and Ti were used for the barrier layer on Si(100). Low temperature (LT) copper buffer layer was introduced and the effect of the buffer on the Cu films was investigated. The grown Cu layers were analyzed using FESEM, XRD, and four point probe measurement. The Cu seed layers were successfully deposited using Cu(dmamb)₂ precursor. Better thickness uniformity was obtained in the Cu films with the LT Cu buffer, which lowered the electrical resistivity.

Ultrananocrystalline diamond (UNCD) films on silicon were prepared by microwave plasma chemical vapor deposition (MPCVD) method using argon-rich CH₄/H₂/Ar plasmas. The graphene sheets synthesized by chemical vapor deposition (CVD) were successfully transferred on to the UNCD surface to fabricate electron field emission (EFE) property-enhanced graphene/UNCD films. The surface morphology, structure and composition of the graphene/UNCD double-layered structures were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), Raman spectroscopy and grazing incidence X-ray diffraction (GXRD). GXRD clearly shows the characteristic diffraction peaks of both diamond and graphene. The Raman spectrum shows the characteristic band of diamond at 1332cm${}^{-1}$ and D, G and 2D bands of graphene at 1360, 1550 and 2610cm${}^{-1}$, respectively. The EFE behavior of the composite films can be turned on at $E_0=2.2$V/$\mu$m, attaining a current density of 0.065mA/cm² at an applied field of 7.3V/$\mu$m.

Single crystal graphene has been getting lots of attention due to the lack of grain boundaries which ensures its distinguished intrinsic properties and good performance in graphene-based devices. Hence, the realization of single crystal graphene growth with tunable size and high crystallinity will be of great importance in commercial production and widespread applications. Recently, numerous studies have focussed on the controlled single crystal graphene growth, and great advancements have been made in the synthesis of large-sized single-crystal graphene (LSSG) by chemical vapor deposition (CVD). In this review, current developments of CVD-grown LSSG and its future prospects are presented and discussed. We emphasize on growth methods and growth mechanisms over transition-metal Cu and Cu alloys for deeper insights in control of size and crystallinity.

Diamond coating has gained intensive attraction in the tribological field due to its high hardness. However, its weak flexibility always gives rise to the fragile crack, which causes the delamination and peeling off from substrate. In this work, a novel deposition method combining the conventional hot filament chemical vapor deposition (HFCVD) and particles doping technique is proposed to balance the hardness and flexibility of diamond coating, by which the diamond coating with tungsten particles is deposited on the co-cemented tungsten carbide substrate. The as-deposited diamond coating is characterized by scanning electron microscopy (SEM) analysis, surface roughness and Raman spectrum. The indentation tests are conducted to evaluate the crack propagation of diamond coating. Tribological behavior is examined on a reciprocating ball-on-plate tribometer. The results indicate that tungsten carbide may be formed between tungsten particles and diamond coating. The W–WC–amorphous carbon–diamond structural coating can validly inhibit the crack propagation and decrease the friction coefficient. Hence, adding embedding particles into the diamond coating may provide a useful way in enhancing the mechanical properties of diamond coating.

Femtosecond (fs) laser ablation has been recognized as an effective and promising technique for high-precision processing of natural and synthesized diamond. In this work, a study of femtosecond laser polishing for nanopolycrystalline diamond (NCD) films by chemical vapor deposition (CVD) is reported. The laser irradiation is induced by 200-fs laser pulses with a repetition frequency of 50MHz, and various laser fluences are employed to investigate their polishing effectiveness. The results show that the optimal laser fluence is 0.7J/cm², at which the nanodiamond grains on top of the cauliflower-like clusters of NCD films can be ablated. With such laser fluence, the mean surface roughness of NCD films reduces from 73.84nm to 31.88nm, which presents a 57% reduction. Nevertheless, when the laser fluence rises beyond 0.7J/cm², large amount of amorphous carbon (a-C) balls and porous lava-like morphology would come into being, resulting in severe degradation of the NCD surface.

This study emphasizes the comparative cutting performance evaluation of CVD- and PVD-coated carbide inserts in hard turning of AISI D2 steel. The cutting factors, namely cutting speed (100m/min), tool feed rate (0.08mm/rev), and depth of cut 0.2mm, have been fixed for the entire study. The comparative study is based on the analysis of the obtained test results of flank wear, tool life, auxiliary flank wear, surface roughness, and surface texture. Both tools are catastrophically failed when tool wear reached limiting flank wear ($\mathrm{\text{VBc}}=0.3$mm) criteria. SEM and EDS analysis of both the tools (at their end of tool life) are carried. Diffusion followed by adhesion is found to be the prime mechanism at the end of tool life. Based on limiting flank wear criteria, the tool life of CVD and PVD tools was estimated as 65 and 57min, respectively, i.e. the tool life of the CVD tool is 14% longer than that of the PVD tool. Considering the limiting criteria of surface roughness ($\mathrm{\text{Ra}}=1.6\mu$m), the tool life of the CVD tool was estimated as 63min while for the PVD tool, it was found as 54min i.e. about 14.3% higher tool life was found for the CVD tool relative to the PVD tool. The auxiliary flank wear was observed to be lower for the CVD tool relative to the PVD tool. Surface roughness for both the tools increased with cutting time and the relatively larger rough surface was obtained with the PVD tool. The machining cost of one pass of the CVD tool is 2.5% less than that of the PVD tool. However, for mass production, the CVD tool is more efficient than the PVD tool for machining hard D2 steel ($57\pm 1$ HRC).

Equal channel angular pressing (ECAP) processed materials have higher grain refinement and strength, and they exhibit more surface roughness when they are machined. This enhancement in the properties highly influences the surface roughness and material removal rate of the materials. The commercial pure aluminum has a wide variety of applications when it is enhanced with high strength properties. In this paper, the machinability of commercially pure aluminum processed through ECAP is investigated in turning operations. Different ECAP processes are carried out to study the microstructural characterization and mechanical properties of the material. The material removal rate and surface roughness are tested by performing the turning operation in the CNC lathe with chemical vapor deposited carbide tool such that the feed rate, spindle speed and depth of cut are considered as the machining variables. To create a hypothesis for the experimentation, the empirical models are developed for the objective functions using the statistical technique response surface methodology (RSM) such that the response models are the objective functions and the model variables are the machining parameters. The response models are verified for the adequacy through ANOVA and $p$-test, and also verified for the closeness with the experimental results. Artificial neural network (ANN)-based empirical equations are also developed for the objective functions using the RSM design matrix and the results of both the RSM and ANN are compared for the suitability.

Direct growth of large-area uniform graphene films on insulating materials could facilitate the applications of graphene in optoelectronic devices. The ultrafast photocarrier relaxation and saturable absorption of direct chemical vapor deposition-grown graphene glasses, with lots of defects, are studied by using femtosecond time-resolved pump–probe and Z-scan techniques at 800 nm. We find that both the relaxation times associated with hot carrier cooling and the hot phonon effect are greatly suppressed in these defect-rich graphene glasses, which further leads to the increase of both saturation intensity and anisotropy in transient optical response for graphene glasses as compared with defect-free graphene. And, both the suppression effect and saturation intensity increase with the thickness of graphene film. The dominance of defect-assisted carrier-acoustic phonon scattering (i.e., supercollision, the collision of a carrier with both an acoustic phonon and defects) in the cooling process of hot carriers is responsible for the suppression of relaxation time.

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