Fibrous monolithic ceramic with a single alumina phase: Fracture and high‐temperature tribological behaviors

Abstract

Fabrication of fibrous monolithic ceramic with bamboo-like structures is a promising method to improve the mechanical properties of ceramics through extrinsic reinforcement. Nevertheless, heterogeneous boundaries are easily oxidized at high temperatures, which seriously limits the long-term use of these materials when employed in high-temperature and high/low-temperature alternating environments. In this study, a "plain" ceramic-a single-component and complex-structure Al 2 O 3 ceramic-was successfully designed and prepared using nano-sized Al 2 O 3 as polycrystalline fibers and micro-sized Al 2 O 3 as boundaries to obtain a structure with a fibrous monolithic architecture. Self-toughening of Al 2 O 3 ceramics can be achieved by introducing hierarchical architectures derived from the difference between grain sizes of fibers and boundaries, which gives the ceramics high fracture toughness and reliability. Moreover, the material demonstrated a low friction coefficient and high wear-resistance properties when coupled with C/C composites at room temperature, 800°C, and in the alternating temperature enviroment between room temperature and 800°C.

Strong and Tough Alumina Ceramic from the Particle‐Stabilized Foam

“…However, it cannot perfectly describe the various external toughening mechanisms that occur during crack propagation, which greatly contribute to the dissipation of energy. [ 39 ] Cracks are deflected along grain boundaries coursed by plate‐like grain, the pullout effect of fractured plate‐like grain, and some other external toughening mechanisms that lead to a steady growth of cracks, similar to fibers. [ 62 ] The stable crack propagation (K JC ) is called R‐curve effect.…”

“…[17,[33][34][35] Therefore, the self-toughening method for in situ growth of highaspect-ratio reinforcements has received extensive attention due to its lower cost and better effect. [36][37][38] Su et al [39] successfully designed and prepared a single-component Al 2 O 3 ceramic with bamboo-like structures using nanosized Al 2 O 3 as polycrystalline fibers and microsized Al 2 O 3 as boundaries. The DOI: 10.1002/adem.202200971 Strength and toughness are two vital and contradictory properties, especially in alumina structural ceramics.…”

“…[ 17,33–35 ] Therefore, the self‐toughening method for in situ growth of high‐aspect‐ratio reinforcements has received extensive attention due to its lower cost and better effect. [ 36–38 ] Su et al [ 39 ] successfully designed and prepared a single‐component Al 2 O 3 ceramic with bamboo‐like structures using nanosized Al 2 O 3 as polycrystalline fibers and microsized Al 2 O 3 as boundaries. The monolithic Al 2 O 3 ceramic exhibited high toughness and graceful failure behavior, and its values of fracture toughness exceeded 7.1 ± 1.1 MPa m 1/2 .…”

Bioinspired alumina/reduced graphene oxide fibrous monolithic ceramic and its fracture responses

“…15,16 In fibrous monolithic ceramics, ceramic matrix fiber cells mainly contribute to the carrying capacity of materials, and cell boundaries induce crack deflection and branching to avoid further extension of the fracture and catastrophic failure. 17 The cell boundary phase is usually a weak interface layer, and is selected based on the ceramic fiber cells to bring them into full collaborative play. This phase also presents proper bonding strength with ceramic fiber cells.…”

Investigation on the Tribological Behaviors of as-sprayed Al2O3 Coatings With the Effects of MoS2 Lubricant and External Loads

“…Ceramic materials are widely used due to making up for the de ciency of metals and alloys. However, due to the high friction coe cient of ceramic materials, it is di cult to achieve the degree of oil-free lubrication [8][9][10]. Therefore, the research on the tribological properties of ceramic materials has been paid attention to the scienti c eld.…”