Effect of ZTA concentration on structural, thermal, mechanical and dielectric behavior of novel ZTA–PVA nanocomposite films

Abstract

Zirconia toughened alumina (ZTA) nanopowder was synthesized by solution combustion technique. Polymer nanocomposites were prepared using ZTA nanopowder as the reinforcement and polyvinyl alcohol (PVA) as the matrix. ZTA nanopowder composition was varied from 0 to 2.5% by weight. Structural characterization was done using scanning electron microscope (SEM) and X-ray diffraction (XRD). XRD results showed prominent, well defined peaks of zirconia and α-alumina, hence confirmed that ZTA is a crystalline material. SEM images showed that, level of agglomeration kept increasing due to increase in filler content, which might have contributed to film stiffness. Thermal analysis was carried out using differential scanning calorimetry. Addition of ZTA into PVA matrix resulted in increase in melting point as well as glass transition temperature. Influence of the nanofiller concentration on the electrical conductivity was found using Agilent 4249A impedance analyser. Conductivity measurements were carried out for all the nanocomposite films doped with ZTA and were found to exhibit insulating properties. Change in mechanical properties such as Young's modulus, tensile strength and film toughness of PVA films as a function of nano filler content are reported.

t‐ZrO2 toughened Al2O3 free‐standing films and as oxidation mitigating thin films on silicon nitride via colloidal processing of flame made nanopowders (NPs)

“…The ZrO 2 content was reduced because typical power electronic ZTA substrates contain < 30 mol% ZrO 2 . [13][14][15] Figure 4 compares the SEM fracture surfaces of films A-D (Table 3) sintered at 1300°C-1500°C/5 h/O 2 (Figure S1A). At 1300°C, all films are not dense, but the grains of 30 mol% ZrO 2 -doped Al 2 O 3 supplemented with TiO 2 (B and C) show significant grain growth compared to films without TiO 2 (A) as expected.…”

“…In this section, the sinterability, microstructures, and fractural toughness of ZTA films up to ~200 µm thick and ~ 2×2 cm 2 were investigated for possible application as power electronic substrates [11][12][13][14] using composition D from the above studies.…”

“…Alumina (Al 2 O 3 ) is a widely studied structural ceramic with applications as grinding media, for cutting tools, high‐temperature engine components, prosthetic implants, and substrates for power electronics due to its high melting point, excellent mechanical strength, hardness, and chemical stability as well as its widespread abundance 1–17 . However, applications using pure α‐Al 2 O 3 are limited by its low resistance to crack propagation, that is, poor fracture toughness (4‐5 MPa m 1/2 ) 18,19 that can lead to catastrophic failure 1–3 .…”

“…While thin films are suitable for applications such as electronic devices and protective coatings, for other structural applications such as wear components, dental composites, and prosthetic implants, bulk materials are also highly desirable. At the interface between bulk and thin films, intermediate thicknesses, for example, up to ~300 µm, are used as electrically insulating layers as well as high‐strength substrates for piezoresistive sensors and power electronics 11–14 . Finally, to test ZTA mechanical properties, greater thicknesses are preferred to prevent cracking caused simply by handling.…”

“…At the interface between bulk and thin films, intermediate thicknesses, for example, up to ~300 µm, are used as electrically insulating layers as well as highstrength substrates for piezoresistive sensors and power electronics. [11][12][13][14] Finally, to test ZTA mechanical properties, greater thicknesses are preferred to prevent cracking caused simply by handling.…”