Two-Stage Sintering of Nb2O5 Doped Zirconia Toughened Alumina (ZTA) Composites

2020 ◽  
Vol 861 ◽  
pp. 327-333
Author(s):  
Teow Hsien Loong ◽  
Se Yong Eh Noum ◽  
Wong Wai Mun
Keyword(s):  
Mechanical Properties ◽  
Hip Replacement ◽  
Niobium Oxide ◽  
Sintering Temperature ◽  
Well Being ◽  
Two Stage ◽  
Total Hip ◽  
Fine Grained ◽  
Second Stage ◽  
Zirconia Toughened Alumina

It is estimated that 130 million people will suffer from osteoarthritis by 2050 which require patient to undergo a surgical procedure known as total hip replacement which has lifespan of 20 years and failure rates of ~1%. This research would highlight the effects of doping Niobium Oxide (Nb2O5) between 0 vol % to 0.8 vol % into Zirconia-Toughened Alumina (ZTA) composites which is the main biomaterials used to manufacture total hip arthroplasty. The samples were sintered using two-stage sintering (TSS) between 1400°C and 1550°C for first-stage sintering temperature at heating rate of 20°C/min. At second stage, the samples were sintered at 1350°C and hold for 12 hours. It was found that TSS combined with addition of Nb2O5 as dopants were beneficial in producing fine-grained ZTA composites with improved mechanical properties compared to undoped ZTA composites produced via TSS. Compared to undoped ZTA composites, samples doped with Nb2O5 and sintered at T1 ≥1400°C were fully densed (>98%), achieved Vickers hardness more than 20 GPa and Young’s modulus higher than 410 GPa and at the same time fracture toughness of more than 8 MPam1/2. Based on the findings, production of ZTA composites with enhanced mechanical properties with longer lifespan is possible which is beneficial in ensuring the well-being of osteoarthritis patients.

The Effect of Ta2O5 on the Densification Behaviour and Mechanical Properties of Zirconia-Toughened Alumina (ZTA) Composites Prepared by Two-Stage Sintering

2020 ◽  
Vol 861 ◽  
pp. 320-326
Author(s):  
Teow Hsien Loong ◽  
Se Yong Eh Noum ◽  
Wong Wai Mun
Keyword(s):  
Mechanical Properties ◽  
Hip Replacement ◽  
Sintering Temperature ◽  
Tantalum Oxide ◽  
Well Being ◽  
Two Stage ◽  
Total Hip ◽  
Second Stage ◽  
Replacement Procedure ◽  
Zirconia Toughened Alumina

By 2050, 130 million people are estimated to suffer from osteoarthritis worldwide which would require patients to undergo total hip replacement procedure which have a lifespan of 20 years and failure rates of ~1%. In this research, Zirconia Toughened Alumina (ZTA) which is the main biomaterial used for total hip arthroplasty were doped with varying vol % of Tantalum Oxide (Ta2O5) from 0 to 0.4 vol % were produced through conventional two-stage sintering with first stage sintering temperature, ranging between 1400°C and 1550°C, heated at 20°C/min, followed by second stage sintering temperature of 1350°C and hold for 12 hours. The efficacy of two-stage sintering on the microstructure and mechanical properties of the sintered samples were then evaluated. Addition of Ta2O5 combined with two-stage sintering were able to produce ZTA composites with enhanced grain size and mechanical properties compared to undoped ZTA composites. The samples with 0.3 vol% Ta2O5 content and above sintered at T1 ≥1450°C achieved density > 99% T.D., Vickers hardness > 19 GPa, Young’s modulus > 400 GPa and fracture toughness > 6 MPam1/2 when compared to undoped ZTA composites. This would enable production of ZTA with improved mechanical properties and lifespan ensuring the well-being of people suffering from osteoarthritis.

scholarly journals Symptomatic trochanteric non-union following total hip replacement treated with reattachment combined with two-stage revision surgery of the femoral stem

2019 ◽  
Vol 101 (6) ◽  
pp. e133-e135
Author(s):  
E Drampalos ◽  
L Bayam ◽  
J Oakley ◽  
M Hemmady ◽  
J Hodgkinson
Keyword(s):  
Total Hip Replacement ◽  
Hip Replacement ◽  
Posterior Approach ◽  
Femoral Stem ◽  
The Other ◽  
Artificial Joint ◽  
Two Stage ◽  
Non Union ◽  
Total Hip ◽  
Second Stage

We present a case of symptomatic trochanteric non-union following total hip replacement treated initially with a Dall-Miles grip plate. After failure of this treatment, the patient had a two-stage revision. Trochanteric non-union is one of the well-described complications after total hip replacement. It is frequently difficult to treat, while potentially causing weakness, altered gait and instability of the artificial joint. We believe that reattachment of the trochanter combined with a staged revision of the femoral stem using a posterior approach for the second stage could be a valuable technique to be added to the orthopaedic armamentarium for recurrent and symptomatic trochanteric non-unions after primary total hip replacement, particularly after failure to treat with all the other techniques described in literature.

Effect of Temperature and Holding Time on Zirconia Toughened Alumina (ZTA) Prepared by Two-Stage Sintering

2021 ◽  
Vol 1030 ◽  
pp. 11-18
Author(s):  
Teow Hsien Loong ◽  
Ananthan Soosai ◽  
Suresh Muniandy
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Young’S Modulus ◽  
Sintering Temperature ◽  
Young's Modulus ◽  
Holding Time ◽  
Effect Of Temperature ◽  
Two Stage ◽  
Pinning Effect ◽  
Zirconia Toughened Alumina

The microstructure and mechanical properties of Zirconia Toughened Alumina (ZTA) produced via two-stage sintering at various sintering temperature of T1 and T2 in addition to effect of various holding time were investigated. T1 temperature was set between the range of 1400°C to 1500°C with a heating rate of 20°C/min. The samples were then sintered at T2 ranging from 1350°C to 1400°C followed by various holding time between 2 hours to 12 hours. The sintered samples’ microstructural properties, bulk density, hardness (Vickers hardness), elastic modulus (Young’s modulus) and fracture toughness (K1C) were then determined. Compared to standard holding time of two-stage sintering which is 12 hours, results show that ZTA produced via two-stage sintering with shorter holding time of 4 hours with T1 set at 1500°C and T2 of 1450°C are capable of achieving full densification. In addition, the same sample were also able to achieve hardness up to 19 GPa, Young’s modulus of 390 GPa and fracture toughness of 6.1 MPam1/2. The improvement in mechanical properties can be mainly attributed to the absent of surface diffusion at T2 above 1400°C and also presence of Y-TZP which contributed to lower grain growth due to the pinning effect.

scholarly journals Effect of Graphene-Oxide Addition on the Microstructure and Mechanical Properties of Two-Stage Sintered Zirconia-Toughened Alumina (ZTA) Composites

2021 ◽  
Vol 335 ◽  
pp. 03019
Author(s):  
Hsien Loong Teow ◽  
Sivakumar Sivanesan ◽  
Se Yong Eh Noum ◽  
Ananthan Soosai ◽  
Suresh Muniandy
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Graphene Oxide ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
High Hardness ◽  
Two Stage ◽  
Total Hip ◽  
Microstructure And Mechanical Properties ◽  
Zirconia Toughened Alumina

United Nations has estimated that 130 million people would suffer from osteoarthritis worldwide by 2050. This disease would require patients to undergo a surgery known as Total Hip Replacement (THR) which has a failure rate of approximately 1 % with a lifespan of 20 years. The biomaterials used to manufacture this total hip artroplasty are mainly made of Zirconia-Toughened Alumina. In this work, Zirconia Toughened Alumina (ZTA) composites with 10 vol% Y-TZP content were doped with small amount (0.01 to 1 wt%) of graphene oxide (GO). The GO-doped ZTA composites were produced via two-stage sintering with T1 ranging between 1400°C and 1550°C, heating rate of 20°C/min, followed by T2 of 1350°C and 12 hours holding time. The sintered ZTA samples were then evaluated on its microstructure and mechanical properties such as bulk density, Vickers hardness, Young’s modulus and fracture toughness to investigate the effect of GO addition on ZTA samples prepared via two-stage sintering. The results showed that ZTA composites containing up 0.1 wt% GO is beneficial in improving the microstructural and mechanical properties of ZTA composites prepared via two-stage sintering. The sample recorded a high hardness of up to 18.5 GPa, Young’s modulus of 406 GPa and fracture toughness of 5.8 MPam1/2 when sintered at T1 of 1450℃.

scholarly journals Knowing What, How and Why: A Near Complete Solution for Aspect-Based Sentiment Analysis

2020 ◽  
Vol 34 (05) ◽  
pp. 8600-8607
Author(s):  
Haiyun Peng ◽  
Lu Xu ◽  
Lidong Bing ◽  
Fei Huang ◽  
Wei Lu ◽  
...  
Keyword(s):  
Sentiment Analysis ◽  
State Of The Art ◽  
Complete Solution ◽  
Unified Model ◽  
Two Stage ◽  
Fine Grained ◽  
Aspect Extraction ◽  
Second Stage ◽  
Opinion Extraction ◽  
Complete Story

Target-based sentiment analysis or aspect-based sentiment analysis (ABSA) refers to addressing various sentiment analysis tasks at a fine-grained level, which includes but is not limited to aspect extraction, aspect sentiment classification, and opinion extraction. There exist many solvers of the above individual subtasks or a combination of two subtasks, and they can work together to tell a complete story, i.e. the discussed aspect, the sentiment on it, and the cause of the sentiment. However, no previous ABSA research tried to provide a complete solution in one shot. In this paper, we introduce a new subtask under ABSA, named aspect sentiment triplet extraction (ASTE). Particularly, a solver of this task needs to extract triplets (What, How, Why) from the inputs, which show WHAT the targeted aspects are, HOW their sentiment polarities are and WHY they have such polarities (i.e. opinion reasons). For instance, one triplet from “Waiters are very friendly and the pasta is simply average” could be (‘Waiters’, positive, ‘friendly’). We propose a two-stage framework to address this task. The first stage predicts what, how and why in a unified model, and then the second stage pairs up the predicted what (how) and why from the first stage to output triplets. In the experiments, our framework has set a benchmark performance in this novel triplet extraction task. Meanwhile, it outperforms a few strong baselines adapted from state-of-the-art related methods.

Partial two-stage exchange of the infected total hip replacement using disposable spacer moulds

2014 ◽  
Vol 96-B (11_Supple_A) ◽  
pp. 66-69 ◽  
Author(s):  
A. V. Lombardi Jr ◽  
K. R. Berend ◽  
J. B. Adams
Keyword(s):  
Total Hip Replacement ◽  
Hip Replacement ◽  
Two Stage ◽  
Total Hip

Magnetic Pulse Compaction of Oxide Powders of the (ZrO2 – Y2O3) – Al2O3 System

2014 ◽  
Vol 1040 ◽  
pp. 819-823 ◽  
Author(s):  
Aleksander S. Ivashutenko ◽  
Nikita Martyushev ◽  
Igor G. Vidayev
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Physical And Mechanical Properties ◽  
Operating Principle ◽  
Magnetic Pulse ◽  
Fine Grained ◽  
Oxide Powders ◽  
Fine Grained Structure ◽  
Ampere’S Law ◽  
Ampère’S Law

Technology for manufacturing products by magnetic pulse compaction from oxide powders of the (ZrO2 – Y2O3) – Al2O3 system is presented in the paper. Diagram of the magnetic-pulse press with its operating principle being based on Ampere's law is given. Physical and mechanical properties of the obtained compacts are determined. The main feature of the designed technology is the reduced sintering temperature (200 °С) and the acquired fine-grained structure of the products. Another significant advantage achieved by applying the technology is the possibility for manufacturing fine-grained structure ceramic products with high mechanical properties.

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