Thermal,electrical, and mechanical properties of addition-type liquid silicone rubber co-filled with Al2O3 particles and BN sheets

The addition-type liquid silicone rubber (ALSR) co-filled with spheroidal Al₂O₃ and flaky BN was prepared by the mechanical blending and hot press methods to enhance the thermal, electrical, and mechanical properties for industrial applications. Morphologies of ALSR composites were observed by scanning electron microscopy (SEM). It was found that the interaction and dispersion state of fillers in the ALSR matrix were improved by the introduction of BN sheets. Thermal, electrical, and mechanical performances of the ALSR composites were also investigated in this work. The result indicated that the thermal conductivity of ALSR can reach 0.64 W m⁻¹ K⁻¹ at the loading of 20 wt% Al₂O₃/20 wt% BN, which is 3.76 times higher than that of pure ALSR. The addition of Al₂O₃ particles and BN sheets also improve the thermal stability of ALSR composites. Moreover, pure ALSR and ALSR composites showed relatively lower dielectric permittivity (1.9–3.1) and dielectric loss factor (<0.001) at the frequency of 10³ Hz. The insulation properties including volume resistivity and breakdown strength were improved by the introduction of flaky BN in the ALSR matrix. The volume resistivity and characteristic breakdown strength E₀ are 6.68 × 10¹⁵ Ω m and 93 kV/mm, respectively, at the loading of 20 wt% Al₂O₃/20 wt% BN. In addition, the mechanical characteristics including elongation at break and tensile strength of ALSR composites were also enhanced by co-filled fillers. The combination of these improved performances makes the co-filled ALSR composites attractive in the field of electrical and electronic applications.     

Development of highly reinforced maleated natural rubber nanocomposites based on sol–gel‐derived nano alumina

In the present study, sol–gel synthesized alumina (Al₂O₃) nanoparticles were characterized by Fourier transform infrared spectra, X‐ray diffraction, field‐emission scanning electron microscopy. Then, Al₂O₃ nanoparticles were employed to improve cure, mechanical, and thermal properties of maleated natural rubber (MNR) nanocomposites. The MNR nanocomposite with 2 phr nano Al₂O₃ exhibited excellent value of cure rate index and exceptionally high value of mechanical properties like modulus and tensile strength in comparison to unfilled MNR compound. Thermogravimetric analysis indicated that nano Al₂O₃ was able to improve the thermal stability of MNR composites to some extent. Additionally, the present study revealed that the interfacial interaction between MNR and nano Al₂O₃ was far better than that between NR and nano Al₂O₃ as confirmed from crosslinking degree measurement and morphological analysis. The present article offers a fresh approach to prepare high performance nano Al₂O₃‐based MNR compounds for future industrial application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46248.     

Properties of nanofillers/crosslinked polyethylene composites for cable insulation

In this work, we report the effect of nanofillers and filler loading on mechanical, physical, dielectric, and thermal properties of the crosslinked polyethylene (XLPE) matrix. XLPE filled with 0.5–2% of zinc oxide (ZnO), aluminium oxide (Al₂O₃), and organoclay (OMMT) nanofillers prepared by melt mixing with a single screw extruder followed by hot press moulding. Nanocomposites were tested as per ASTM standard methods and characterized with tensile test, water absorption, linear rate of burning, dielectric breakdown strength, and thermal stability. Scanning electron microscopy (SEM) was used to examine the surface morphology of the nanocomposites. The results showed that addition of nanofillers improved tensile strength, elongation at break, Young's modulus, burning rate, dielectric breakdown strength, and decomposition temperature. However, water absorption increased with time due to the hydrophilic properties of nanofillers. In general, based on the properties measured Al₂O₃ exhibits the highest properties than those of ZnO and OMMT nanofillers. Addition of 1.5% of Al₂O₃ in XLPE matrix has led to the improvement in tensile strength, elongation at break, Young's modulus, burning rate, and dielectric breakdown strength as compared to the unfilled polymer. J. VINYL ADDIT. TECHNOL., 25:E147–E154, 2019. © 2018 Society of Plastics Engineers     

Lap shear strength and thermal stability of diglycidyl ether of bisphenol a/epoxy novolac adhesives with nanoreinforcing fillers

Nanoreinforcing fillers have shown outstanding mechanical properties and widely used as reinforcing materials associated to polymeric matrices for high performance applications. In this study, a series of multiwalled carbon nanotubes (MWCNTs)‐, nano‐Al₂O₃‐, nano‐SiO₂‐, and talc‐reinforced epoxy resin adhesives composites were developed. The influence of different types and contents of nanofillers on adhesion, elongation at break, and thermal stability (under air and nitrogen atmospheres) of diglycidyl ether of bisphenol A (DGEBA)/epoxy novolac adhesives was investigated. A simple and effective approach to prepare adhesives with uniform and suitable dispersion of nanofillers into epoxy matrix was found to be mechanical stirring combined with ultrasonication. Transmission electron microscopic and scanning electron microscopic investigations revealed that nanofillers were homogeneously dispersed in epoxy matrix at optimized nanofiller loadings. Adhesion strength was measured by lap shear strength test as a function of nano‐Al₂O₃ and MWCNTs loadings. The results indicated that the lap shear strength was significantly increased by about 50% and 70% with addition of MWCNTs and nano‐Al₂O₃ up to a certain level, respectively. The highest lap shear strength was reached at 1.5 wt % of nano‐Al₂O₃ loading. MWCNTs at all loadings (except 3 wt %) and nano‐Al₂O₃ have enhanced onset of degradation temperature and char yield of the adhesives. By combined incorporation of 0.75 wt % nano‐Al₂O₃ and 0.75 wt % MWCNTs into the epoxy novolac/DGEBA blend adhesives a synergistic effect was observed in the thermal stability of the adhesives at high temperatures (800°C). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40017.     

Novel heat‐conductive composite silicone rubber

The silicone rubber with good thermal conductivity and electrical insulation was obtained by taking vinyl endblocked polymethylsiloxane as basic gum and thermally conductive, but electrically insulating hybrid Al₂O₃ powder as fillers. The effects of the amount of Al₂O₃ on the thermal conductivity, coefficient of thermal expansion (CTE), heat stability, and mechanical properties of the silicone rubber were investigated, and it was found that the thermal conductivity and heat stability increased, but the CTE decreased with increasing Al₂O₃ fillers content. The silicone rubber filled with hybrid Al₂O₃ fillers exhibited higher thermal conductivity compared with that filled with single particle size. Furthermore, a new type of thermally conductive silicone rubber composites, possessing thermal conductivity of 0.92 W/mK, good electrical insulation, and mechanical properties, was developed using electrical glass cloth as reinforcement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2478–2483, 2007     

Mechanical properties,chemical and aging resistance of natural rubber filled with nano‐Al2O3

Al₂O₃ nanoparticles were introduced to natural rubber (NR) to investigate its reinforcement effect on filled NR vulcanizates. The results show that Nano‐Al₂O₃/NR nanocomposites exhibit significantly improved tensile strength, elongation at break, modulus, and tearing strength. Scanning electron microscopy analyses indicate that nanoparticles dispersed in NR matrix at nanoscale and show nano‐reinforcement effect on NR vulcanizates. The aging resistances of filled NR vulcanizates improve. After aging test, tensile strength, tearing strength, and modulus improved, and elongation at break decreased. These attribute to the crosslink maturation reactions, which result in the conversion of polysulfidic linkages into disulfidic and monosulfidic ones. The acid and alkaline resistances of nano‐Al₂O₃‐filled NR vulcanizates improve compared with that of unfilled NR systems. After acid and alkaline test, tensile strength and elongation at break improve, and modulus decrease. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Preparation,structures and properties of interpenetrating network structure-type Phosphate/PEEK composites with enhanced compressive strength and high temperature resistance

Phosphate/polyether ether ketone (PEEK) composites were successfully prepared by molding method and thermal treating at the temperature of 360 °C. The structures and compositions of phosphate/PEEK composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy. The mechanical properties thermal resistance and dielectric properties were strictly evaluated by the mechanical testing, thermogravimetric analysis and dielectric constant analysis. As the results, the interpenetrating network structure (IPNS) of Al₂O₃-phosphates was completely formed in PEEK matrix. And the phosphate/PEEK composite with 40% Al₂O₃-phosphate showed a 15.9% increasing for tensile strength and 74.5% increasing for compressive strength at room temperature. Besides, the phosphate/PEEK composite with 80 wt% Al₂O₃-phosphate dispalyed a dielectric constant of 4.0, a dielectric loss of 0.0601 and a Shore hardness of 91 HD. As the structural materials, these composites would exhibited the potential applications in aviation, aerospace and other fields.     

Enhanced dielectric and mechanical properties of CaCu3Ti4O12/Ti3C2Tx MXene/silicone rubber ternary composites

Dielectric polymer composites with conducting fillers would have great potential for diverse applications if their severe leakage loss could be addressed. In this regard, ternary composites using both ceramic and conducting materials as fillers might be an enabler for high dielectric constant and low dielectric loss. Herein, ternary composites with both Ti₃C₂T_x MXene conducting nanosheets and CaCu₃Ti₄O₁₂ (CCTO) dielectric particles embedded in silicone rubber were studied. It was found that a ternary composite with 1.2 wt% (0.40 vol%) Ti₃C₂T_x MXene and 12 wt% (2.58 vol%) CCTO could provide an overall superior performance that include a high dielectric constant of 8.8, low dielectric loss of less than 0.0015, good thermal stability up to 450 °C, and excellent mechanical properties with tensile strength of 569 kPa, elastic module of 523 kPa and elongation at break of 333%. The outstanding performance is attributed to the improved uniform dispersion and good interfacial compatibility of mixed fillers in the polymer matrix, suggesting ternary composites might be a better option over their binary counterparts in preparing high performance dielectric composites.     

Properties of thermally conductive silicone rubbers filled with admicellar polymerized polypyrrole-coated Al2O3 particles

Polypyrrole (PPy) nanolayers were introduced on the surface of alumina (Al₂O₃) particles via admicellar polymerization. The properties of silicone rubbers (SRs) filled with PPy-coated Al₂O₃ and pristine Al₂O₃ as thermally conductive fillers were studied and compared. The results demonstrate that the addition of PPy-coated Al₂O₃ leads to a better interfacial compatibility but lower cross-linking density of the composites than pristine Al₂O₃. The improvement in the compatibility and the decrease in the cross-linking density are paradoxes in affecting mechanical properties. The improvement in the compatibility shows a slight predominance on the strength at low-filler contents. Lower cross-linking density of modified-Al₂O₃/SR composites led to a better processing performance and a higher maximum filler loading amount than the pristine Al₂O₃/SR composites, which is beneficial to increasing the thermal conductivity and maintaining a relatively good strength. The PPy-coated Al₂O₃/SR composite with 83 wt% filler content has a thermal conductivity of 1.98 W/(m K) and a tensile strength of 2.9 MPa, and the elongation at break was 63%. Functionalized fillers by admicellar polymerization used in the fabrication of filler/SR composites not only improve the interfacial compatibility but also optimize and expand the functions of the composites, which has great significance for the production and application of thermally conductive SR in some branches of industry (automotive, electrical engineering, etc.) in the future.     

Effect of Al2O3 addition on thermo‐electrical properties of polymer composites: An experimental investigation

To develop a new class of composites with adequately high thermal conductivity and suitably controlled dielectric constant for electronic packages and printed circuit board applications, polymer composites are prepared with microsized Al₂O₃ particle as filler having an average particle size of 80–100 μm. Epoxy and polypropylene (PP) are chosen as matrix materials for this study. Fabrication of epoxy‐based composite is done by hand lay‐up technique and its counterpart PP‐based composite are fabricated by compression molding technique with filler content ranging from 2.5–25 vol%. Effects of filler loading on various thermal properties like effective thermal conductivity (k_eff), glass transition temperature (T_g), coefficient of thermal expansion (CTE) and electrical property like dielectric constant (ε_c) of composites are investigated experimentally. In addition, physical properties like density and void fraction of the composites along with there morphological features are also studied. The experimental findings obtained under controlled laboratory conditions are interpreted using appropriate theoretical models. Results show that with addition of 25 vol% of Al₂O₃, k_eff of epoxy and PP improve by 482% and 498% respectively, T_g of epoxy increases from 98°C to 116°C and that of PP increases from −14.9°C to 3.4°C. For maximum filler loading of 25 vol% the CTE decreases by 14.8% and 26.4% for epoxy and PP respectively whereas the dielectric constants of the composites get suitably controlled simultaneously. POLYM. COMPOS., 36:102–112, 2015. © 2014 Society of Plastics Engineers     

Electrical insulation characteristics of alumina,titania, and organoclay nanoparticles filled PP/EPDM nanocomposites

In this study, nanofillers composed of alumina, titania, and organoclay were separately embedded in 50% polypropylene (PP) and 50% ethylene propylene diene monomer (EPDM) blends. Several formulations of PP/EPDM nanocomposites were prepared using an internal mixer and were molded using a compression mold to produce test samples. The effects of filler loading (2, 4, 6, and 8 vol %) on the dielectric breakdown strength, dielectric properties, hydrophobicity, and flammability were determined. The addition of nanofillers improved the breakdown strength (up to 2 vol %) and increased the dielectric constant and dielectric loss of the PP/EPDM nanocomposites. The hydrophobicity of PP/EPDM/Al₂O₃ increased, whereas the hydrophilicity of PP/EPDM/TiO₂ and PP/EPDM/organoclay increased. Flammability test results showed that PP/EPDM/TiO₂ had a lower burning rate than PP/EPDM/Al₂O₃ and PP/EPDM/organoclay. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41184.     

Low-temperature sintering and microwave dielectric properties of 3Z2B glass–Al2O3 composites

A potential low temperature co-fired ceramics system based on zinc borate 3ZnO–2B₂O₃ (3Z2B) glass matrix and Al₂O₃ filler was investigated with regard to phase development and microwave dielectric properties as functions of the glass content and sintering temperature. The densification mechanism for 3Z2B–Al₂O₃ composites was reported. The linear shrinkage of 3Z2B glass–Al₂O₃ composites exhibited a typical one-stage densification behavior. XRD patterns showed that a new crystalline phase, ZnAl₂O₄ spinel, formed during densification, indicating that certain chemical reaction took place between the 3Z2B glass matrix and the alumina filler. Meanwhile, several zinc borate phases, including 4ZnO·3B₂O₃, crystallized from the glass matrix. Both of the reaction product phase and crystallization phases played an important role in improving the microwave dielectric properties of composites. The optimal composition sintered at 850–950 °C showed excellent microwave dielectric properties: ?_r = ∼5.0, Q·f₀ = ∼8000 GHz, and τ_f = ∼−32 ppm/°C at ∼7.0 GHz.     

Tribological behavior of micrometer‐ and nanometer‐Al2O3‐particle‐filled poly(phthalazine ether sulfone ketone) copolymer composites used as frictional materials

Micrometer‐ and nanometer‐Al₂O₃‐particle‐filled poly(phthalazine ether sulfone ketone) (PPESK) composites with filler volume fractions ranging from 1 to 12.5 vol % were prepared by hot compression molding. We evaluated the tribological behaviors of the PPESK composites with the block‐on‐ring test rig by sliding PPESK‐based composite blocks against a mild carbon steel ring under dry‐friction conditions. The effects of different temperatures on the wear rate of the PPESK composites were also investigated with a ball‐on‐disc test rig. The wear debris and the worn surfaces of the PPESK composites were investigated with scanning electron microscopy, and the structures of the PPESK composites were analyzed with IR spectra. The lowest wear rate, 7.31 × 10^?6 mm³ N^?1 m^?1, was obtained for the composite filled with 1 vol %‐nanometer Al₂O₃ particles. The composite with nanometer particles exhibited a higher friction coefficient (0.58–0.64) than unfilled PPESK (0.55). The wear rate of 1 vol %‐nanometer‐Al₂O₃‐particle‐filled PPESK was stable and was lower than that of unfilled PPESK from the ambient temperature to 270°C. We anticipate that 1 vol %‐nanometer‐Al₂O₃‐particle‐filled PPESK can be used as a good frictional material. We also found that micrometer‐Al₂O₃‐particle‐filled PPESK had a lower friction coefficient at a filler volume fraction below 5%. The filling of micrometer Al₂O₃ particles greatly increased the wear resistance of PPESK under filler volume fractions from 1 to 12.5%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 993–1001, 2005     

Preparation and properties of nano‐Al2O3 particles/polyester/epoxy resin ternary composites

This article presents the results of an experimental study on the preparation and properties of new ternary composites composed of nano‐Al₂O₃ particles, polyester, and epoxy resin. The ternary composites were prepared by the addition of the nano‐Al₂O₃ particles in a binary matrix, with elevated viscosity, of the epoxy resin modified by the polyester. The nano‐Al₂O₃ particles were previously located and dispersed in the polyester phase. The study showed that the ternary system was a type of nanoscale dispersed composite with high strength and toughness as well as modulus, combined with excellent dielectric and heat‐resistance properties. All related properties of the composites were remarkably superior to those of both the binary matrix and the unmodified epoxy resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 70–77, 2002     

Effect of MAPP on interfacial compatibility of wood flour/polypropylene composite evaluated with dielectric approach

To quantitatively evaluate the effect of maleic anhydride grafted polypropylene (MAPP) as a coupling agent on interfacial compatibility between wood and polymer in wood/polypropylene (PP) composite, the dielectric constant and dielectric loss factor were measured for poplar (Populus tomentasa Carr.) wood flour/polypropylene (PP) composites prepared with six MAPP loading levels (0.5, 1.0, 1.5, 2.0, 4.0, and 8.0%), and the Cole–Cole plots, the dielectric relaxation strength, the distribution of relaxation time and the activation thermodynamic quantities of the dielectric relaxation based on the reorientation of the methylol groups (CH₂OH) in the amorphous region of wood cell wall were further analyzed. The results showed that the dielectric relaxation strength decreased with the MAPP loading and dropped to the lowest at MAPP loading of 2.0%, after which it kept almost constant. It suggested that the internal bonding between wood and PP molecules was the strongest at 2.0% MAPP, therefore the reorientation of the methylol groups in wood became very difficult under the strong hindrance from the long‐chained PP molecules and the physical or/and chemical bonds between MAPP, wood flour, and PP in the composites. The activation free energy ΔE could be served as the indicator to quantitatively evaluate the effect of MAPP on interfacial compatibility of the wood/PP composites. ΔE of 2.0% MAPP modified composites showed the maximal value among all the tested conditions, which was 33.52 kJ mol⁻¹; while the values for 1.5 and 4.0% MAPP modified were 23.35 and 21.75 kJ mol⁻¹. Therefore, excessive MAPP was not beneficial to improve the internal compatibility of wood/PP composites, but had negative effect. POLYM. COMPOS., 35:489–494, 2014. © 2013 Society of Plastics Engineers     

Fabrication of alumina based electrically conductive polymer composites

Novel electrically conductive composites were synthesized by incorporating Cu coated alumina (Cu‐Al₂O₃) powder prepared via electroless plating technique as filler (0–21wt %) into polystyrene‐b‐methylmethacrylate (PS‐b‐PMMA) and polystyrene (PS) matrices. XRD analysis depicted maximum Cu crystallite growth (26.116 nm～ plating time 30 min) onto Al₂O₃ along with a significant change in XRD patterns of composites with Cu‐Al₂O₃ inclusion. SEM–EDX analyses exhibited uniform Cu growth onto Al₂O₃ and confirmed presence of Cu, Al, Pd in Cu‐Al₂O₃, and C, O, Al, Cu, and Pd in PS‐b‐PMMA and PS composites. Increasing filler loadings exhibited increased electrical conductivity (5.55 × 10^?5S/cm for PS‐b‐PMMA; 5.0 × 10^?6S/cm for PS) with increased Young's modulus (1122MPa for PS‐b‐PMMA; 1053.9MPa for PS) and tensile strength (27.998MPa for PS‐b‐PMMA; 30.585MPa for PS) and decreased % elongation. TGA demonstrated increased thermal stability and DTG revealed two‐step degradation in composites while DSC depicted pronounced increment in T_g of Cu‐Al₂O₃/PS‐b‐PMMA with increased filler loading. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42939.     

Novel Al2Mo3O12-PTFE composites for microwave dielectric substrates

Nowadays, microwave dielectric substrate materials have been extensively investigated to meet the requirements of rapid development in modern communications. Among them, the composites of ceramic powder filled polytetrafluoroethylene (PTFE) have been a hot topic. However, the compatibility and connectivity between the surface of ceramics and PTFE molecular chains in the samples are usually low. Herein novel PTFE based composites with different contents of Al₂Mo₃O₁₂ (20–60 wt%) modified by C₁₄H₁₉F₁₃O₃Si (F8261) coupling agent were designed and prepared. The coupling agent F8261 has been successfully grafted to the surface of Al₂Mo₃O₁₂ powders, effectively promoting the densification and dielectric properties of the composites. As the content of the modified Al₂Mo₃O₁₂ powders increases from 20 to 60 wt%, the ε_r value increases from 3.4 to 4.2, and tanδ almost remains constant at the beginning and increases with much more Al₂Mo₃O₁₂ added. The Al₂Mo₃O₁₂-PTFE composites filled with 30 wt% Al₂Mo₃O₁₂ present the optimal dielectric properties of ε_r = 3.6 and tanδ = 0.0018 with a high density of 95.6%. In addition, the electromagnetic and multiphysic simulation of a 24 GHz substrate integrated waveguide filter on the basis of the 30 wt% Al₂Mo₃O₁₂ - 70 wt% PTFE composite was carried out. It was revealed that the filter presented high stability on the electrical parameters caused by self-heating and dimension deformation due to the good microwave dielectric, thermal and mechanical properties of the substrate. These results indicate that the as-prepared 30 wt% Al₂Mo₃O₁₂ - 70 wt% PTFE composite would be a promising candidate for high-performance microwave dielectric substrates.     

Thermal aging on ethylene–propylene–diene rubber composites reinforced by samarium oxide,samarium borate and Sb in Sb doped SnO2

Abstract

Ethylene–propylene–diene monomer (EPDM) rubber composites reinforced with 50 phr samarium oxide (Sm₂O₃), samarium borate (SmBO₃) and Sb in antimony doped tin oxide (ATO) are aged at 150°C for different intervals. It is found that neutral Sm₂O₃ and alkaline SmBO₃ can retard the oxidative degradation of EPDM by blocking radical passage. The acidic ATO particles can accelerate the oxidative degradation of EPDM. The trend of tensile strength of EPDM composites is consistent with that of cross-link density of EPDM composites. SmBO₃ and ATO can retard the increase of dielectric loss until 10 days of aging, while Sm₂O₃ can keep the dielectric loss at low level until 14 days of aging. The increased surface charge of filler can make surface and volume resistivity decrease sharply. Antimony doped tin oxide can deteriorate the dielectric strength of EPDM, while SmBO₃ and Sm₂O₃ can keep the dielectric strength of EPDM at a constant level.     

High-temperature mechanical property and thermal shock resistance of Al2O3f/Al2O3 composites

Continuous alumina fiber–reinforced alumina matrix composites (Al₂O_3f/Al₂O₃ composites) were produced via sol–gel process, then the high-temperature mechanical property and thermal shock resistance of Al₂O_3f/Al₂O₃ composites were investigated. The results showed that the composites exhibited excellent high-temperature properties. The mechanical property of the composites was affected by heat treatment (prepared at 1100°C exhibited the most desirable mechanical property). The tensile strength of the composites abruptly decreased at higher temperatures. Although the mechanical property of the composites deteriorated after the thermal shock test was conducted at high temperatures, they exhibited excellent thermal shock resistance. After 50 thermal shock tests conducted at 1300 and 1500°C, the flexural strength of the composites was found to be 124.34 and 93.04 MPa, thus showing a decrease in strength with the increasing temperature.     

Enhanced dielectric breakdown strength in Ni2O3 modified Al2O3-SiO2-TiO2 based dielectric ceramics

Dielectric ceramics have raised particular interest since they enable pulsed-power systems to achieve high voltage gradient and compact miniaturization. In this work, x wt%Ni₂O₃ doped Al₂O₃-SiO₂-TiO₂ based dielectric ceramics were prepared using conventional solid-state reaction and the effects of Ni₂O₃ on the crystal structure, dielectric properties and dielectric breakdown strength were investigated. It was found that with the doping of Ni₂O₃, the Al₂O₃-SiO₂-TiO₂ based dielectric ceramics became denser and the distribution of each phase was more uniform. For the composition of x?=?2.0, the dielectric breakdown strength was increased into 82.1?kV/mm, more than twice compared with that of the undoped one. In addition, the relationship between the dielectric breakdown strength and the resistance of Al₂O₃-SiO₂-TiO₂ based dielectric ceramics was discussed. The results show that the doping of Ni₂O₃ is a very feasible way to improve the dielectric breakdown strength and optimize the dielectric properties for the Al₂O₃-SiO₂-TiO₂ based dielectric ceramics.