Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay

Este es un artículo de acceso abierto distribuido bajo los términos de una licencia de uso y distribución CC BY-NC 4.0. Para ver

una copia de esta licencia visite http://creativecommons.org/licenses/by-nc/4.0/ 14

Additive Manufacturing of Cupric Oxide via Direct Ink Writing

Fabricación aditiva de óxido cúprico mediante escritura directa con tinta

Fabricação aditiva de óxido cúprico por escrita direta de tinta

Muhammad Ali

, Shaheryar A. Khan

(*), Aqueel Shah

, Antash Najib

, Abbas Hussain

Recibido: 18/08/2025 Aceptado: 24/11/2025

Summary. - The DIW approach offers numerous benefits, including expedited prototyping, cost-effectiveness, reduced

waste in manufacturing, and enhanced design flexibility. It's currently a popular production method for building

materials and has great potential for porous and electronic materials. In this study, porous cupric oxide (CuO) ceramics

were fabricated using a direct ink writing (DIW) approach based on a copper particle–laden aqueous precursor. The

ink formulation was optimized to achieve stable extrusion and crack-free green bodies, yielding a final composition of

68.0 wt% Cu, 31.3 wt% water, and 0.6 wt% CMC. Following oxidation and sintering in air, the printed structures

exhibited a bulk density of 3.60 ± 0.20 g cm⁻³ and a corresponding theoretical porosity of 43.7 ± 0.9%. X-ray diffraction

confirmed nearly phase-pure monoclinic CuO with no detectable Cu or Cu₂O residues. The printed components

exhibited an interconnected, porous microstructure and a four-point-probe resistivity of 10.5 ± 0.3 Ω·m at 25 °C,

reflecting the influence of high porosity on charge transport. The DIW route demonstrated here provides a controllable

pathway for producing porous CuO architectures with tunable microstructure and moderate electrical conductivity.

These characteristics suggest potential applicability in gas filtration, catalytic supports, and electrochemical sensing;

however, device-level validation is still required to fully assess functional performance.

Keywords: Advanced Ceramics, Direct Ink Writing, Additive Manufacturing, Copper Oxide, Cupric Oxide, Binder,

Ceramics, Green Body, Brown Body, Sintered Ceramic, Resistivity Analysis of Ceramic, Aqueous Binder Slurry,

Particle Laden Slurry

(*) Corresponding author.

Postgraduate Student, National University of Sciences and Technology (Pakistan), ime.322.ali@gmail.com,

ORCID iD: https://orcid.org/0009-0006-8014-5737

Associate Professor and Head of the Department of Mechanical Engineering., DHA Suffa University (Pakistan), shaheryar.atta@dsu.edu.pk,

ORCID iD: https://orcid.org/0000-0003-1600-7322

Professor, National University of Sciences and Technology (Pakistan), a.shah@smme.nust.edu.pk,

ORCID iD: https://orcid.org/0000-0003-2814-3073

Assistant Professor, National University of Sciences and Technology (Pakistan), antash.najib@pnec.nust.edu.pk,

ORCID iD: https://orcid.org/0000-0002-4845-9350

Assistant Professor, National University of Sciences and Technology (Pakistan), abbas.hussain@pnec.nust.edu.pk,

ORCID iD: https://orcid.org/0009-0008-1680-6507

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 15

Resumen. - El método DIW ofrece numerosas ventajas, como la creación rápida de prototipos, la rentabilidad, la

reducción de residuos en la fabricación y una mayor flexibilidad de diseño. Actualmente es un método de producción

popular para materiales de construcción y tiene un gran potencial para materiales porosos y electrónicos. En este

estudio, se fabricaron cerámicas porosas de óxido cúprico (CuO) utilizando un método de escritura directa con tinta

(DIW) basado en un precursor acuoso cargado con partículas de cobre. La formulación de la tinta se optimizó para

lograr una extrusión estable y cuerpos verdes sin grietas, obteniendo una composición final de 68,0 % en peso de Cu,

31,3 % en peso de agua y 0,6 % en peso de CMC. Tras la oxidación y sinterización al aire, las estructuras impresas

mostraron una densidad aparente de 3,60 ± 0,20 g cm⁻³ y una porosidad teórica correspondiente de 43,7 ± 0,9 %. La

difracción de rayos X confirmó CuO monoclínico casi puro en fase, sin residuos detectables de Cu o Cu₂O. Los

componentes impresos exhibieron una microestructura porosa interconectada y una resistividad de cuatro puntas de

10,5 ± 0,3 Ω·m a 25 °C, lo que refleja la influencia de la alta porosidad en el transporte de carga. La ruta de impresión

directa con tinta (DIW) demostrada aquí proporciona una vía controlable para producir arquitecturas porosas de

CuO con microestructura ajustable y conductividad eléctrica moderada. Estas características sugieren una posible

aplicabilidad en filtración de gases, soportes catalíticos y detección electroquímica; sin embargo, aún se requiere una

validación a nivel de dispositivo para evaluar completamente su rendimiento funcional.

Palabras clave: Cerámica avanzada, Impresión directa con tinta, Fabricación aditiva, Óxido de cobre, Óxido cúprico,

Aglutinante, Cerámica, Cuerpo verde, Cuerpo marrón, Cerámica sinterizada, Análisis de resistividad de cerámica,

Suspensión acuosa de aglutinante, Suspensión con partículas

Resumo. - A abordagem de escrita direta de tinta (DIW) oferece inúmeros benefícios, incluindo prototipagem

acelerada, custo-benefício, redução de desperdício na fabricação e maior flexibilidade de design. Atualmente, é um

método de produção popular para materiais de construção e tem grande potencial para materiais porosos e

eletrônicos. Neste estudo, cerâmicas porosas de óxido cúprico (CuO) foram fabricadas utilizando uma abordagem de

escrita direta de tinta (DIW) baseada em um precursor aquoso carregado com partículas de cobre. A formulação da

tinta foi otimizada para obter extrusão estável e corpos verdes sem trincas, resultando em uma composição final de

68,0% em peso de Cu, 31,3% em peso de água e 0,6% em peso de CMC. Após oxidação e sinterização ao ar, as

estruturas impressas apresentaram uma densidade aparente de 3,60 ± 0,20 g cm⁻³ e uma porosidade teórica

correspondente de 43,7 ± 0,9%. A difração de raios X confirmou a presença de CuO monoclínico quase puro, sem

resíduos detectáveis de Cu ou Cu₂O. Os componentes impressos exibiram uma microestrutura porosa interconectada

e uma resistividade de quatro pontos de 10,5 ± 0,3 Ω·m a 25 °C, refletindo a influência da alta porosidade no transporte

de carga. A rota DIW demonstrada aqui fornece um caminho controlável para produzir arquiteturas porosas de CuO

com microestrutura ajustável e condutividade elétrica moderada. Essas características sugerem potencial

aplicabilidade em filtração de gases, suportes catalíticos e sensores eletroquímicos; no entanto, a validação em nível

de dispositivo ainda é necessária para avaliar completamente o desempenho funcional.

Palavras-chave: Cerâmicas Avançadas, Impressão Direta de Tinta, Manufatura Aditiva, Óxido de Cobre, Óxido

Cúprico, Aglutinante, Cerâmicas, Corpo Verde, Corpo Marrom, Cerâmica Sinterizada, Análise de Resistividade de

Cerâmica, Suspensão Aquosa de Aglutinante, Suspensão com Partículas

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 16

Graphical abstract.

1. Introduction. - The demand for materials with enhanced performance has created an everlasting need for the

emergence of advanced materials. In today’s world, advanced ceramics have primarily supplanted traditional materials.

This technological change is motivated and boosted by the Asian markets in Japan and China [1].

Ceramics are well-known materials among other inorganic materials for their peculiar characteristics due to their

chemical and physical properties [2]. High hardness, high strength, low thermal conductivity, and biocompatibility are

some of the unique characteristics of advanced ceramics [3–6]. These materials have an enhanced resistance to wear

governed by their microstructures that enable their application in various areas such as aerospace, biomedical, solar

cells, fuel cells, heat exchangers, turbines, and piezo-electric devices [7].

Cupric oxide (CuO) is a black-colored ceramic material known as cupric oxide or copper (ii) oxide [8]. It is a transition

metal oxide with a high surface-to-volume ratio, porosity, and monoclinic crystal structure [9,10]. It holds unique

importance due to its comparable efficiency as a catalytic agent, superconducting property, anti-microbial agent, and

energy-storing characteristics [9,11,12]. It is used in various domains today, including electronics, biomedical devices,

energy harvesting systems, chemical catalysts for different chemical reactions, solid self-lubricants, and anti-microbial

textiles [13–15]. It is used as a p-type semiconductor and magnetic storage media, finding its application in capacitors,

electrodes, and different gas-sensing probes [16–19]. It is used to sense gases in the atmosphere and different

biomedical sensing devices, including but not limited to CO2, NO2, H2, H2S, CO, benzyne, alcohol, ethanol, and

methanol [10,20–24]. Studies show that CuO has the potential to replace the graphite anodes in lithium-ion batteries,

as it is less expensive, safer, and more environmentally favorable than graphite [25]. CuO-based biomedical instruments

detect blood protein patterns and blood glucose levels [16]. CuO also serves the environment by removing pollutants

from the aqueous environment, including fluorides, arsenic, benzene, and toluene [26–28]. Its adsorption property

removes lead, acrylic acid, and ciprofloxacin from different media, making CuO a good choice as a water-treating agent

[26].

Conventional techniques for producing monolithic ceramic parts have many disadvantages, such as reliance on molds,

lengthy production cycles, low material utilization rate, high material waste, high production cost, limited production

volume, poor repeatability, and lack of microstructure control. [29]. These techniques include dry pressing, casting,

micromachining, and injection molding [30,31]. Dry pressing and casting have similar limitations, such as the

requirement for molds and the inability to produce complex shapes readily [32]. Fractures, porosity, and warpage are a

few of the defects that can occur during the dry pressing and casting of ceramics. Nevertheless, these processes are

protracted processes that frequently result in a product with an unstable microstructure [30].

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 17

Micromachining in ceramics is limited to low-volume production due to the high cost of the required machining tools,

the geometric constraints that impede the production of intricate patterns, and the material's fragility [30].

Additive manufacturing (AM) has disrupted the manufacturing space and is being utilized to circumvent the limitations

of conventional manufacturing techniques [33–35]. The technique builds monolithic parts layer-by-layer using 3D

CAD data, resulting in the fabrication of complex geometries and reducing machining costs [36–38]. The technique

provides freedom of design, increased finish quality, and reduced design-to-production lead time [39].

AM techniques have been developed for different materials [40,41], however, the Direct Ink Writing (DIW) technique

is the most flexible, which can additively manufacture polymers, metals, ceramics, composites, and biological materials

[42–44]. The DIW technique employs viscous pastes termed “inks” to produce monolithic parts [45]. The inks can be

loaded with particles of ceramics to produce ceramic green bodies that can be later sintered in a furnace to produce a

monolithic ceramic part [46]. Furthermore, pre-ceramic metal powder may also be utilized, which will oxidize in the

furnace to produce ceramic parts[47].

The composition of the ink can be customized based on the specific application and desired properties of the printed

part [43]. The combination of solid particles, solvents, binders, surfactants, plasticizers, rheology modifiers, and

crosslinkers allows for a wide range of ink formulations that can be optimized for different printing methods, materials,

and part geometries [45,48–51].

Despite extensive research on DIW of ceramic materials, the additive manufacturing of cupric oxide remains largely

unexplored, particularly when derived from metallic copper precursors. Existing DIW studies on ceramics primarily

utilize oxide powders, sol–gel routes, or UV-curable suspensions, whereas the transformation of a water-based metallic

copper ink into a monolithic CuO ceramic through controlled oxidation and sintering has not been previously reported.

In this study, we establish a reproducible process window for printing crack-free CuO structures using an aqueous

CMC-based binder formulation with optimized copper loading. The work further demonstrates that the resulting 3D-

printed CuO exhibits a combination of high porosity and measurable electrical conductivity, enabling its potential use

in sensing and filtration applications. This contribution distinguishes the present study from prior DIW efforts and

provides a scalable, low-cost pathway for fabricating functional CuO architectures.

This paper presents the additive manufacturing of copper oxide via the Direct Ink Writing (DIW) technique. A pre-

ceramic green body was produced using an aqueous ink loaded with copper particles. The green body was sintered to

form a monolithic ceramic part and characterized for its density, structure, and electrical conductivity. The results

demonstrate that DIW is a viable technique for the manufacturing of monolithic parts from CuO. Unlike most existing

DIW ceramics that utilize oxide powders, sol-gel routes, or UV-curable suspensions, this work establishes the first

reported transformation of a water-based metallic copper ink into a monolithic CuO ceramic through a controlled

oxidation and sintering process.

2. Materials and methods. - Copper powder, DI water (De-Ionized Water), and CMC (Carboxymethyl Cellulose)

binder were the three components used for this research. Copper powder with a particle size of 10µm was purchased

and imported from Vanuatu. The DI water was used in this experiment to ensure that no impurity was added to the

materials during the manufacturing process, affecting the chemical composition of the slurry. CMC binder, holding

CAS number 9000-11-7, was purchased from Purge Chemical Industries, Karachi, Pakistan.

2.1 Preparation of copper-loaded pre-ceramic ink. - The pre-ceramic ink was formulated as a copper particle–laden

aqueous binder system. The aqueous binder was first prepared by dissolving 0.20 g of CMC in 10.0 g of deionized

water, followed by manual stirring for 3 minutes to ensure complete homogenization. Subsequently, 21.7 g of copper

powder was incorporated into the binder solution. The copper powder was added intermittently and stirred continuously

to promote uniform wetting and dispersion. Manual stirring throughout this process ensured homogeneous distribution

of the metallic particles within the aqueous matrix. The final ink composition on a mass–mass basis consisted of 68.0

wt% copper, 31.3 wt% water, and 0.6 wt% CMC.

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 18

Multiple solid loadings were evaluated to identify the optimal formulation for DIW. Copper contents lower than 68

wt% resulted in insufficient structural integrity during drying, leading to cracking of the green bodies. Conversely,

higher copper loadings produced excessively dense pastes that consistently clogged the nozzle during extrusion. The

polymeric binder concentration also governed drying behaviour: CMC levels above 0.6 wt% increased shrinkage and

deformation during solvent removal, whereas lower binder contents led to cracking due to inadequate particle–particle

bridging. Based on these observations, the composition of 68.0 wt% Cu and 0.6 wt% CMC in a 31.3 wt% aqueous

phase was identified as the optimal mass fraction combination for achieving stable extrusion, shape retention, and

crack-free green bodies.

Although the ink was formulated and optimized on a mass–mass basis, its rheological behavior was also considered

during process development, as DIW printability is strongly governed by viscosity, shear-thinning characteristics, and

yield stress. While full rheological profiling (e.g., viscometry or oscillatory shear measurements) was not performed in

this study, the formulation exhibited all qualitative indicators of DIW-compatible flow behavior. Specifically, the ink

demonstrated continuous filament formation under extrusion, maintained structural integrity after deposition, and

showed no signs of uncontrolled spreading, all of which are consistent with shear-thinning pastes reported in DIW

literature. The absence of nozzle clogging or die swell further suggests that the yield stress lies within a suitable range

for stable extrusion. The optimized solid and binder mass fractions (68.0 wt% Cu and 0.6 wt% CMC) were therefore

selected not only for their influence on drying and green-body integrity, but also for their empirically validated

rheological performance during printing.

2.2 Direct Ing Writing. - Parts were manufactured using a modified Creality Ender-3 platform that was adapted for

direct ink writing (DIW) through mechanical and control-system modifications. The stock thermoplastic extruder

assembly was removed and replaced with a custom-designed DIW print head. The print head consisted of a 50 mL

pneumatic dispensing cartridge fitted with a tapered nozzle of 0.4 mm exit diameter, which deposited the copper-loaded

pre-ceramic slurry onto a glass build platform. Extrusion was actuated by a regulated pneumatic pressure system

(0–1 MPa), supplied by a laboratory compressor and controlled by an electronic solenoid valve interfaced with the

printer’s control board. Fine adjustment of the extrusion pressure was achieved using an inline pressure regulator to

ensure stable and continuous filament formation.

The Ender-3 is originally designed for stepper-driven thermoplastic extrusion and, therefore, its firmware was modified

so that the E-axis extrusion commands in the G-code toggled the solenoid valve rather than driving a stepper motor.

Geometric parameters, including layer height, nozzle speed, infill pattern, and wall thickness, were defined in the slicing

software (Ultimaker Cura), while the extrusion rate was governed exclusively by pneumatic pressure. These

modifications enabled reliable deposition of the high-viscosity CuO precursor paste while preserving the positional

accuracy inherent to the FFF motion system.

All samples were manufactured under controlled laboratory conditions of 25 ± 1 °C and 50% relative humidity. Fig. 1

illustrates the modified DIW setup along with the part geometry selected for DIW-based CuO ceramic fabrication, and

the corresponding DIW process parameters are summarized in Table 1. The printed aerofoil specimen (NACA 2412)

had an overall chord length of 100 mm, a maximum thickness of 15.54 mm, and a span of 3 mm (z-axis). The outer

shell thickness was set to 0.8 mm, with a rectilinear infill density of 100%. These dimensions were chosen to minimize

drying-induced warpage and to promote uniform shrinkage during sintering.

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 19

Figure I. The Direct Ink Writing (DIW) setup.

Parameter

Value

Nozzle Diameter

0.4 mm

Layer Height

0.2 mm

Extrusion Width

0.4 mm

Linear Speed

20 mm.s-1

Raster Angle

45 degrees

Infill Pattern

Rectilinear

Infill Density

100%

Wall thickness

0.8 mm

Air Pressure

0.2 MPa

Table I. Parameters of the Direct Ink Writing Process.

2.3 Drying, demolding, and sintering. - The printed green bodies were dried at room temperature for 24 h and

subsequently sintered in a programmable air furnace concurrently. The temperature schedule consisted of an initial

heating step from room temperature to 400 °C at a rate of 5 °C/min, followed by a dwell of 45 min to ensure complete

binder burnout. The temperature was then increased from 400 to 900 °C at 5 °C/min, where the samples were held for

180 min to promote oxidation and densification. After sintering, the furnace was allowed to cool naturally to room

temperature at an uncontrolled rate. All specimens were sintered in ambient air without additional oxygen flow. The

multi-step sintering regime is illustrated in Figure II.

Figure II. The Direct Ink Writing (DIW) setup.

3. Results and discussion. -

3.1 Sintered ceramic body. - The transformation of the DIW sample to the final sintered ceramic body is illustrated

in Figure III. The technique can produce monolithic parts using pre-ceramic slurry without cracking and warping. An

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 20

isotropic shrinkage of 4.1 ± 0.2 % (n=5) was observed from the CAD model to the sintered body. It can be concluded

that the DIW technique is a viable option for the manufacturing of monolithic ceramic parts. Simple and complex part

geometries can be designed in a CAD environment and implemented readily for function-specific applications.

Figure III. Transformation from the DIW part to the sintered monolithic ceramic body (Aerofoil Geometry).

3.2 XRD Analysis. - The X-ray diffractogram of the sintered CuO sample is illustrated in Figure IV. The XRD analysis

demonstrates that the Cu particles have uniformly oxidized into CuO as the experimental pattern shows an excellent

match with the monoclinic CuO reference pattern (Crystallography Open Database) [52]. A quantitative analysis by

Rietveld refinement using FullProf software was performed to identify the phase ratio. The results of the refinement

indicated that the sample is 99.8 % phase-pure CuO. No significant secondary phases, such as residual Cu or Cu2O,

were detected above the instrument's detection limit.

The degree of crystallinity was determined by integrating the area under the crystalline peaks and the background

amorphous hump. Using the peak analyser tool in OriginLab software, the crystallinity degree of the sample was

calculated to be 65.78%.

The crystallite size of the XRD patterns was estimated using Scherrer's equation:

   

  󰇛󰇜

where D is the crystallite size, k is the so-called shape factor (0.9), λ is the wavelength (0.15418 nm, CuKα), β is the

Full Width at Half Maximum (FWHM), and θ is the diffraction angle [53]. To ensure an accurate representation, the

crystallite size was calculated using the FWHM of the three most intense peaks: (111 ), (111), and (200) located at

approximately 35.5°, 38.7°, and 39.8° 2Theta, respectively). The FWHM values were corrected for instrumental

broadening using a standard LaB6 reference sample. Exploiting the average of the data derived from these three peaks,

an average crystallite size of 71.75 nm was determined, with an estimated standard deviation (error) of 2.1 nm is

reported for the measurement. The sample was identified as having a Monoclinic Crystal System with refined lattice

parameters.

Figure IV. X-ray diffractogram of sintered CuO sample.

M. Ali, S. A. Khan, A. Shah, A. Najib, A. Hussain

Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 14-29

https://doi.org/10.36561/ING.30.3

ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 21

The refined lattice parameters of the sintered phase were found to be a = 4.68370 Å, b = 3.42260 Å, c = 5.12880 Å,

and β = 99.54°. These values are in excellent agreement with the reported unit-cell dimensions for monoclinic CuO

(tenorite), which are typically quoted as a ≈ 4.68 Å, b ≈ 3.42 Å, c ≈ 5.13 Å, and β ≈ 99.5° in standard crystallographic

databases and the literature. The close match between the extracted parameters and the reference values indicates that

the as-sintered material is phase-pure CuO with negligible lattice distortion. Any minor differences are within expected

experimental uncertainty and may arise from instrument calibration, residual micro-strain introduced during the

oxidation/sintering cycle, or slight non-stoichiometry. Peak broadening observed in the diffractogram (Scherrer

crystallite size ≈ 72 nm) is consistent with the finite crystallite size and could also contribute to small uncertainties in

the refined cell metrics.

3.3 Morphology. - The morphology of copper powder and the sintered CuO ceramic was studied under a Scanning

Electron Microscope. SEM micrographs of copper powder in Fig. 5 (a and b) depict the powder having an average

particle size of 10μm. The SEM micrographs demonstrate the agglomeration of the copper powder. The copper powder

was not subjected to ball milling to prevent it from early oxidation.

Figure V (c and d) shows the SEM images of the CuO sintered sample manufactured using additive manufacturing.

The micrographs show that powder particles have sintered into a porous structure. This porosity allows for the

application of additively manufactured CuO parts in applications such as gas sensing and pollutant filtration [54].

Figure V. (a) SEM image of copper powder at x100 magnification. (b) SEM image of copper powder at x200

magnification. (c) SEM image of sintered CuO ceramic at x200 magnification. (d) SEM image of sintered CuO

ceramic at x500 magnification.

3.4 Porosity and Density. - The surface porosity of the sintered sample was estimated through pixel intensity analysis

using the ImageJ software. Pixel intensity analysis is illustrated in Figure VI, where the porous regions are mapped

with red color. The software estimates a mean surface porosity of 40.4%.

(a)

(b)

(c)

(d)