Hot Jet Research Articles

Numerical study on the asymmetrical jets formation from active pre-chamber under super-lean combustion conditions

This paper aims to investigate the mechanism of the asymmetric jets of the TJI system. We analyzed the effects of fuel injection and air flows in pre-chamber and main chamber, initial flame kernel, and evolution of turbulent hot jets. The evaluation indexes of asymmetric jet were proposed. The results show when adding fuel injection into the homogeneous PC with off-central spark plug, the average relative velocity range and average degree of velocity non-uniformity increased by 50.8% and 32.8%, which increased by 75.1% and 46.7% for the real engine condition with intake airflow and fuel injection. A similar phenomenon was observed for central spark plug settings but with a much stronger impact on the asymmetry of jets velocity as proved by the increment of 138.5% and 93.2% under real engine condition. The asymmetric jets can be divided into the asymmetry of jets size and the asymmetry moment of flame jets. The former of different jets’ velocity is attributed to the tumble flow in main chamber. The latter is attributed to the irregular flame propagation caused by the off-central ignition and the uneven mixture distribution in pre-chamber. The optimization strategies to efficiency utilize the flow exchange between PC and MC were proposed.

Numerical Investigation on Detonation Initiation and Propagation with a Symmetric-Jet in Supersonic Combustible Gas

In this study, supersonic gaseous detonation initiation and propagation by single- and symmetric-jets are compared, and the effects of symmetric-jets of different intensities on the detonation are further investigated to obtain a more comprehensive understanding of the initiation mechanism of hot jet in supersonic mixtures. The two-dimensional reactive Navier–Stokes equations, together with a one-step Arrhenius chemistry model, are adopted to analyze the flow field structure. The results show that the bow shocks induced by symmetric-jets interacting with each other will achieve local detonation combustion. Influenced by the unstable shear layer behind the triple point, a large-scale vortex shedding is formed in the flow field, thus promoting the consumption of the unburned region. By comparing with the single-jet, it is found that the dual-jet initiation method can shorten the distance to complete initiation, but has little effect on the detonation overdrive degree. In addition, a study of the impact of jet size parameters on the symmetric-jet initiation further revealed that there is a critical value, above which the ignition decreases rapidly which is a significant advantage over single-jet. However, below this threshold, detonation initiation will rely on the energy generated by the collision of Mach stems formed at the walls, resulting in a slower ignition rate compared to a single-jet. Therefore, the use of the appropriate jet strength when using a symmetric-jet will result in a more desirable ignition velocity and a shorter distance to achieve detonation.

Atomic Layer Thermopiles: Comprehensive static calibration, comparison and application in subsonic and supersonic flows

This paper compares the calibration of different heat flux sensors in radiation- and convection-based sub- and supersonic operation. First, four heat flux sensors based on different principles: ALTP (Transverse Seebeck Effect), HFM-8E (differential-layer device), coaxial Thermocouple and a TG-2000 (circular-foil gage) are calibrated in a laser-based radiation setup. In a second step, all heat flux sensors are compared with a slug-calorimeter within a subsonic convection-dominated facility based on stagnation-point measurements of an impinging hot air jet. The obtained results indicate that a sensitivity transfer between a radiative calibrated sensor used in a mainly convective environment is not always possible and can lead to significant, systematic errors. Calibration in a subsonic shear flow with thermocouple readings demonstrate small divergence from the manufacturer provided sensitivity. Finally, supersonic testing with high frequency shock-boundary layer interactions highlight the need for ALTP rather than the conventional use of thermocouple arrays to resolve the high frequency phenomena associated with shock boundary layer interactions.

Ignition of hexane-air mixtures by highly under-expanded hot jets

We report an experimental study of ignition of flammable mixtures by highly unexpanded, supersonic hot jets. The high-pressure, hot-gas reservoir supplying the jet is created by impacting a projectile on a plunger to rapidly compress and ignite a rich n-hexane/air mixture, resulting in a peak reservoir pressure of more than 20 MPa. A locking mechanism was used to prevent the plunger from rebounding and the jet was created by rupturing a diaphragm covering a nozzle with an exit diameter between 0.25 and 1 mm. The jet development and ignition processes in the main chamber filled with hexane-air mixture were visualized using high-speed schlieren and OH* chemiluminescence imaging. The ignition threshold was determined as a function of composition in the jet and main chamber, the nozzle diameter, and the initial pressure in the main chamber. Unlike the case of subsonic jets in which ignition occurs at the shear layer near the nozzle exit, ignition of combustion in the main chamber was found to take place downstream of the Mach disk terminating the supersonic expansion and within the turbulent mixing region created by the startup of the supersonic jet. The results are interpreted using a constant-pressure, well-stirred reactor model simulating the mixing between the hot jet and cold ambient gas. The critical conditions for ignition are determined by the competition between energy release due to chemical reactions initiated by the hot jet gas and cooling due to mixing with the cold chamber atmosphere. The critical value (maximum for which ignition occurs) of the mixing rate was computed using a detailed chemical reaction model and found to be a useful qualitative guide to our observations.

High-temperature erosion and its mechanisms of IN-738 superalloy under hot air jet conditions

High-temperature erosion and its mechanisms of IN-738 superalloy under hot air jet conditions

Numerical study on initiation of oblique detonation wave by hot jet

Reliable detonation initiation is critical in detonation engines, especially for oblique detonation engines covering a wide range of flight regimes. The widely-studied oblique shock initiation usually leads to a significant variation in initiation length, making it difficult to adapt to the wide range of flight conditions. In this study, hot jets in the induction zone, i.e. behind the oblique shock, are introduced to explore the possibility of jet initiation, providing a potential method for initiation control. Results show that hot jet can decrease the initiation length to achieve rapid initiation and change the wave structure simultaneously, which is attributed to the oblique shock induced by a gaseous wedge. Thermal analyses of jet-initiated ODWs are also conducted through total pressure recovery. Results indicate that jet-initiated ODWs have a slightly better total pressure recovery than the original ODW. Furthermore, the jet angle and position are varied to analyze their effects on the initiation position, which is insensitive to the former while sensitive to the latter. A large jet angle may lead to a strong solution of secondary oblique detonation, which has not been previously reported.

Techno functional characterization of green-extracted soluble fibre from orange by-product

This work studies the techno-functional properties of the spray dried water-soluble extracts from orange pomace, obtained from different green extraction technologies. Orange pomace, a by-product from the juice production industry, was used for soluble fibre extraction. Starting from pomace, four extraction procedures were assayed: hot water, extrusion + hot water, jet cooker and jet cooker + hot water. After treatments, the supernatant was spray dried with whey protein isolate to obtain soluble fibre enriched powders. Microstructure by field emission scanning electron microscopy, color, particle size, moisture content, hydration properties, foaming capacity and stability, rheology, and glass transition temperatures were assayed. All powders exhibited an orange shade. In microstructure, particle size, and glass transition temperature, the powder obtained from extrusion + hot water presented a different behavior from the other powders: less caking and agglomeration, and smaller particles. Also, this powder showed the highest foaming stability and viscosity, as well as glass transition temperature, properties that make it interesting for the food industry. Through valorization of orange pomace fiber-enriched powders could be obtained; these powders can be used as ingredients in the industry to address the fibre gap and provide technological functionalities.

Numerical Investigation on the Performance of a 4-Stroke Engine with Different Passive Pre-Chamber Geometries Using a Detailed Chemistry Solver

Pre-chamber turbulent jet ignition represents one of the most promising techniques to improve spark ignition engines efficiency and reduce pollutant emissions. This technique consists of igniting the air-fuel mixture in the main combustion chamber by means of several hot turbulent flame jets exiting a pre-chamber. In the present study, the combustion process of a 4-stroke, gasoline SI, PFI engine equipped with a passive pre-chamber has been investigated through three-dimensional CFD (Computational Fluid Dynamics) analysis. A detailed chemistry solver with a reduced reaction mechanism was employed to investigate ignition and flame propagation phenomena. Firstly, the combustion model was validated against experimental data for the baseline engine configuration (i.e., without pre-chamber). Eventually, the validated numerical model allowed for predictive simulations of the pre-chamber-equipped engine. By varying the shape of the pre-chamber body and the size of pre-chamber orifices, different pre-chamber configurations were studied. The influence of the geometrical features on the duration of the combustion process and the pressure trends inside both the pre-chamber and main chamber was assessed and discussed. Since the use of a pre-chamber can extend the air-fuel mixture ignition limits, an additional sensitivity on the air-fuel ratio was carried out, in order to investigate engine performance at lean conditions.

Impacts of low atmospheric pressure on distribution of indoor hot air jet in plateau area

The existing design parameters of hot-air heating for local buildings do not consider the distinctive low-pressure that can be experienced in the plateau regions, resulting in significant inefficiency. In this study, a numerical model based on the Reynolds time-averaged method coupled with the RNG k–ε turbulence model was established by considering the air thermal properties influenced by pressure. Four atmospheric conditions of 101.325 kPa, 84.547 kPa, 70.093 kPa and 57.708 kPa were selected to simulate the velocity and temperature fields of the horizontal and vertical hot-air jets. The influence of low pressure on the flow characteristics of hot-air jets was analyzed subsequently. The results suggest the jet flow patterns are essentially similar under various pressures. The horizontal hot-air jets bent upward more significantly and the diffusion range of the vertical jets was reduced under low pressure. The jet velocity decayed faster at low pressure, and the axial velocity of a vertical jet at 57.708 kPa was 0.26 m/s lower than that at 101.325 kPa. The temperature gradient of the room with a hot-air jet was increased with decreasing pressure, which was 5.0 K/m at 57.708 kPa. This study should be helpful to the detailed design and efficient operation of hot-air heating in buildings in the plateau regions.

Numerical Simulation of Orbit Controlled Hot-gas Lateral Jet of the triangular plate with rudder

Hypersonic interception weapons have high requirements for the efficiency and accuracy of the control system. As an effective control approach, the thermochemical non-equilibrium effect of jet flow must be considered in order to accurately predict the aerodynamic characteristic. At present, relevant researches are mostly focused on the low-flow rate hot jet, while numerical simulation and wind tunnel test studies on high-flow rate hot jet are rare. In this paper, the interaction flow field of the rail-controlled jet at the altitude of 60Km and 70Km has been simulated by solving the three-dimensional viscous fluid governing equations. The influence of the thermalchemical non-equilibrium effect of the jet interaction on the flow field characteristics and aerodynamic characteristics of the aircraft was analyzed. The primary results show that: (1) The flow fields of the cold-gas jet, frozen-gas jet and hot-gas jet have significant differences under the high-flow rate jet condition, which is mainly reflected the size and the pressure value of the separation region before the nozzle. The separation region length of the cold-gas jet is approximately twice that of the hot-gas jet and the length of the frozen-gas jet is between them; (2)Jet interaction will increase the surface pressure of the aircraft and reduce the skin-friction. When Ma=25, the aerodynamic interaction of hot jet is only about 30% of that of cold jet; (3) Jet interaction on aerodynamic characteristics increases with altitudes. With the increase of Mach number, the difference between the predicted results of hot jet and cold jet is enlarged because of the enhancement of the thermochemical non-equilibrium effect.

The impact of gasoline formulation on turbulent jet ignition

Turbulent jet ignition (TJI) is a promising technology for burning ultra-lean mixtures; the process is comprised of hot reactive jets issuing from a pre-chamber (PC) and initiating combustion in the main chamber (MC). The present study employs a simplified zero-dimensional (0D) partially stirred reactor (PaSR) model to describe the complex mixing and reaction progress within the PC and its subsequent impact on the MC combustion in terms of combustion efficiency and pollutant formation characteristics. Full three-dimensional (3D) computational fluid dynamics (CFD) data are used to calibrate the PC model, which is subsequently linked to predict the MC combustion behavior. We propose a model to predict the effects of the fuel formulations with varying research octane number (RON) and octane sensitivities (OS) on the TJI performance. After a careful parametric study, a dedicated merit function for identifying the optimal TJI operating conditions was proposed to assess multiple fuel properties and their influence on MC combustion. The model properly accounts for micro-mixing effects in the early jet expansion phase, and represents the effects of a PC jet on enhancing flammability and pollutant mitigation. It was demonstrated that aromatic content affects not only the progress of the thermokinetic runaway, but also the importance of NO formation paths in MC (N2O vs NNH routes), and the effect of the PC jet on MC flammability limits. Among the jet active species, OH and NO exhibited the greatest chemical impact on MC reactivity, while the chemical effects of CO2 and H2O remained limited. The overall fuel TJI merit function showed optimum performance for fuels with 2 < OS < 6 and high RON, similar to the requirements for spark-ignited engine operation beyond motor octane number (MON) conditions, fuel lean advanced compression ignition operation, and spark-induced compression ignition.

Elevated temperature erosion performance of plasma sprayed NiCrAlY/TiO2 coating on MDN 420 steel substrate

The current study deals with the erosion behaviour of a plasma-sprayed 70% NiCrAlY + 30% TiO2 coating on MDN 420 steel substrate at extreme temperatures. The coating was characterized by using an optical microscope, Scanning Electron Microscopy and X-ray diffraction methods. The coating’s porosity, microhardness, surface roughness, and adhesion strength were all examined. The solid particle erosion experiments were carried out at temperatures of 300 °C, 500 °C, and 700 °C, with impact angles of 30° and 90°. The tests were conducted by using the alumina as an erodent in the hot air jet erosion testing machine. The erosion volume loss of coated and uncoated samples was measured using an optical profilometer. It is observed that erosion resistance of the coating was found to be more when compared to the substrate for the different test temperatures chosen. As the temperature increases, the erosion resistance of the coating also found increased from 300 °C to 700 °C at both impact angles of 30° and 90°. The morphology of the eroded coating surface reveals that the generalized behaviour of the coating is ductile in nature.

Different green extraction technologies for soluble dietary fibre extraction from orange by‐product

SummaryThe aim of this work was to extract soluble dietary fibre from orange by‐product, by testing four different green (non‐contaminant, solvent free) extraction technologies: hot water (HW), extrusion + hot water (EHW), jet cooker (JC) and jet cooker + hot water (JCHW). Starting from orange pomace, the treatments were assayed and sample was separated in soluble and insoluble fractions. The processing and analysis of the soluble fraction was continued, through subsequent spray drying until obtaining a soluble fibre‐enriched powder. Powders were analysed: dietary fibre, sugar profile and bioactive characterisation (total polyphenol content, antioxidant capacity). Through the application of these green technologies, it was possible to obtain a functional ingredient with soluble dietary fibre from orange by‐product. EHW was the treatment that yielded the highest amount of soluble dietary fibre, the lowest content of glucose, sucrose and fructose, and the highest polyphenol content and antioxidant capacity.

Study on the ignitability of a high-pressure direct-injected methane jet using a scavenged pre-chamber under a wide range of conditions

Natural gas is a promising alternative fuel for internal combustion engines, it allows for a reduction of engine-out emissions without impairing high engine efficiencies. Although this approach is already utilized from small to large engine classes, it is almost exclusively based on the combustion of a premixed homogeneous charge. For ignition, small engines use standard spark plugs or pre-chambers, while large and lean-operated engines use pre-chambers and pilot injections. Direct high-pressure gas injection is a more recent, alternative way to operate gas engines which offers benefits compared to premixed operation such as high combustion pressures, leaner operation, easier quantity regulation, and higher compression ratios, among others. However, in contrast to diesel injection, the compression temperatures are too low for the auto-ignition of the gas jets. Therefore, an additional ignition system is required, usually a pilot injection system is used. In this study, the usability and performance of a scavenged pre-chamber used for the ignition a high-pressure gas jet has been investigated in an optically accessible test-rig that is able to operate at engine-like conditions. Results show that the turbulent hot jet generated by the pre-chamber was able to ignite the high-pressure gas jet under a wide range of operating conditions. Moreover, it also appears to be a promising ignition strategy for very early direct injection during the compression stroke as well as for port injection. The good performance is attributed to the intense mixing of the main gas jet with the hot jet exiting the pre-chamber.

Experimental Investigation on the Combustion Characteristics of NH3/H2/air by the Spark Ignition and Turbulent Jet Ignition

ABSTRACT In the current work, the combustion of NH3/H2/air blends is experimentally investigated in a constant-volume combustion chamber in terms of two different ignition modes: spark ignition (SI) mode and turbulent jet ignition (TJI) mode with ammonia and hydrogen fueled in the pre-chamber. The results show that for the SI mode, the burning rate and propagation of premixed NH3/air flames are significantly accelerated by a hydrogen addition of only 3% (v/v). A cellular structure is observed and becomes more intense with the increasing hydrogen volume fraction. For the TJI mode, the hot jet generation and turbulent flame development of ammonia inside the main chamber are captured optically for the first time. The combustion process inside the main chamber can be categorized into three phases for both the TJI-ammonia and TJI-hydrogen modes. The cold jet that mainly contains the unburned fuel and air is observed under the TJI-hydrogen mode. The hot jet produced by the pre-chamber can effectively promote the ignition initiation and hence flame propagation in the main chamber. An accelerated burn rate of ammonia is obtained, and the TJI-hydrogen mode makes a stronger promoting impact on the combustion of the main chamber. Significantly, compared with SI-hydrogen mode, the TJI-hydrogen mode can bring a considerable promoting effect to ammonia combustion with significantly lower hydrogen consumption.

Numerical Investigation of the Flow and Infrared Radiation Characteristics of Nozzles with Transverse Jets of Different Shapes

The hot jet of an aero engine is one of the main radiation sources of infrared detectors in 3–5 microwave bands. Transverse jets were introduced into a hot jet to enhance mixing and reduce the infrared radiation characteristics. This proved to be a high-efficiency and low-resistance infrared suppression technology. The steady-state distribution of temperature data was simulated, which was needed in the thermal radiation calculation. The radiation characteristics were calculated based on the anti-Monte Carlo method in 3–5 microwave bands. The mechanics of enhanced mixing by a rectangular nozzle or transverse jets was investigated with the LES simulation. Compared with an axisymmetric nozzle, a rectangular nozzle induced abundant counter-rotating vortex pairs (CVP), hairpins, shears, and helical vortexes, which resulted in significant mixing enhancement and infrared radiation decrease of the hot jets. Further, circumferential transverse jets of different types were introduced downstream of the nozzle. These jets enhanced the mixing and reduced the infrared radiation in the 3–5 µm band. The mixing characteristics of these different schemes were studied in detail. Large-scale vortices formed on the windward portion of the hot jet boundary under the effect of the transverse jets, which caused strong CVP structures. They also resulted in hairpin vortexes, shear vortexes, and helical vortexes appearing earlier and occurring more frequently than with nozzles without transverse jets. The enhanced mixing caused by the transverse jets led to an increase in temperature decay and a decrease in infrared radiation in the 3–5 µm band. Further, transvers jets of different geometrical shapes (rectangular, cube, and circular schemes) achieved different mixing characteristics, and the rectangular transverse jets allowed the most significant mixing for the largest Q criterion value.

Correlation analysis of flow and sound in non-isothermal subsonic jets based on large eddy simulations

The sound radiation mechanism is investigated in non-isothermal subsonic jets at acoustic Mach number 0.9 and at temperature ratios of 0.86, 1.0, and 2.7, using causality methods on the results predicted by large eddy simulations. Turbulence signals in the jet flows are rearranged according to the acoustic analogies, such as the streamwise and radial shear signals, ux′ and ur′, the self-signal, ui′uj′, the entropy fluctuation, s′, and the vortex norm, |ω|. The ray-tracing method is applied to locate the acoustically correlated regions, and the two-point correlation is employed to analyze the acoustic correlation. The results show that the cancelation between the s′ and ux′, and between the s′ and ur′, vary with temperature ratio, and, thus, may affect the radiation directionality. The density fluctuation, ρ′, suppresses the acoustic correlations of the shear- and self-signals in the cold jet, respectively, but strengthens them in the hot jet; thus, the ρ′ enhances the cancelation both in cold and in hot jets. The intense negative fluctuation of the ux′ is found to be associated with the cancelation mechanism. It induces the peaks of ρ′ and s′ by disturbing the average fields. The jet temperature changes the averaged density and entropy so as to change the cancelation mechanism. Two large-scale acoustically correlated parts of the coherent structures are visualized by the zonal correlation of the ρ′. Their acoustic correlations cancel each other in the hot jets, but enhance each other in the cold jets. The acoustically correlated regions represented by the zonal correlations of the s′ and |ω| are in small scale and gather around the end of the potential core region.

Study on the Characteristics of Water Jet Injection and Temperature Spatial Distribution in the Process of Hot Water Deicing for Insulators

For the benefit of knowing the method of insulator deicing using hot water, this paper investigated the physical aspects of propagation and the spatial temperature distribution of a hot water jet in the air. The numerical calculation model for the water jet flow field was established and validated, and the temperature spatial variation rule and influencing factors of the water jet were analyzed. The results indicate that the water column breaks as the distance increases. The numerical calculation results and the experimental results of the water jet flow field were approximated. As the distance increases, the mass entrainment rate of the water jet gradually increases, and the normalized axis velocity decreases approximately linearly. The jet temperature rises with the rise in the initial temperature of the hot water, and the rising rate decreases with the increase in distance. The temperature of the water jet falls as the jet distance increases. With the rise in the outlet pressure, the temperature of the water jet drops slightly. The influence of environmental wind speed on the water jet temperature is more significant than ambient temperature—the water jet temperature increases as the nozzle diameter increases. The thorough deicing efficiency is most outstanding when the hot water output temperature is around 86 °C and the jet pressure is ~3.5 MPa.

X-Ray Emission from the Jets and Lobes of the Spiderweb

Abstract Deep Chandra and Very Large Array imaging reveals a clear correlation between X-ray and radio emission on scales ∼100 kpc in the Spiderweb radio galaxy at z = 2.16. The X-ray emission associated with the extended radio source is likely dominated by inverse Compton upscattering of cosmic microwave background photons by the radio-emitting relativistic electrons. For regions dominated by high surface brightness emission, such as hot spots and jet knots, the implied magnetic fields are ∼50–70 μG. The nonthermal pressure in these brighter regions is then ∼9 × 10−10 dynes cm−2, or three times larger than the nonthermal pressure derived assuming minimum energy conditions, and an order of magnitude larger than the thermal pressure in the ambient cluster medium. Assuming ram pressure confinement implies an average advance speed for the radio source of ∼2400 km s−1 and a source age of ∼3 × 107 yr. Considering the lower surface brightness, diffuse radio-emitting regions, we identify an evacuated cavity in the Lyα emission coincident with the tail of the eastern radio lobe. Making reasonable assumptions for the radio spectrum, we find that the relativistic electrons and fields in the lobe are plausibly in pressure equilibrium with the thermal gas and close to a minimum energy configuration. The radio morphology suggests that the Spiderweb is a high-z example of the rare class of hybrid morphology radio sources (or HyMoRS), which we attribute to interaction with the asymmetric gaseous environment indicated by the Lyα emission.

Mechanical and microMechanical and microstructural characterization of yttria-stabilized zirconia (Y2O3/ZrO2; YSZ) nanopartstructural characterization of yttria stabilized zirconia (Y2O3/ZrO2; YSZ) nanoparticles reinforced WC-10Co-4Cr coated turbine steel

The aim of this paper is to investigate the WC-10Co-4Cr coatings reinforced with 5 % and 10 % of yttria-stabilized zirconia (Y2O3/ZrO2; YSZ) nanoparticles deposited on the CA6NM turbine steel by using the high-velocity oxy-fuel (HVOF) thermal spraying technique. In the HVOF technique, the hot jet of the semi-solid particles strikes against the workpiece and creates a layer of coating of varying thickness on the substrate material. The coatings fabricated with HVOF were analyzed by scanning electron microscope (SEM) / energy-dispersive x-ray spectroscopy (EDS). The phase identification of a crystalline material was made with the x-ray diffraction (XRD) technique. The mecha­nical properties in terms of porosity, surface roughness and microhardness of the nanocomposite coatings were also evaluated. The SEM/EDS analysis showed that dense and homogeneous coatings were developed by the reinforcement of YSZ nanoparticles. The peaks of XRD graphs of WC-10Co-4Cr coating reinforced with 5 and 10 % of YSZ nanoparticles revealed that the WC was present as a major phase and W2C, Co3W3C, Co, Co6W6C, Co6W and Y2O3/ZrO2 nanoparticles were observed as a minor phase. The porosity level decreased up to 42 and 56 % by the addition 5 and 10 % of YSZ nanoparticles as compared with conventional WC-10Co-4Cr coating. The surface roughness values for WC-10Co-4Cr conventional coating, 95 % (WC-10Co-4Cr) + 5 % YSZ and 90 % (WC-10Co-4Cr) + 10 % YSZ nanocomposite coated samples were found to be 5.03, 4.89 and 4.28 respectively. The nanocomposite coatings reinforced with 10 % YSZ nanoparticles exhibited the highest microhardness value (1278 HV). The WC-10Co-4Cr coatings reinforced with 10 % of YSZ nanoparticles resulted in low porosity, low surface roughness and high microhardness. During the coating process, the nanoparticles of YSZ flow into the pores and are dispersed in the gaps between the micrometric WC particles and provide a better shield to the substrate material. The WC-10Co-4Cr with 10 % of YSZ nanoparticles showed better results in terms of mecha­nical and microstructural properties during the investigation.