Periodic Reporting for period 1 - GLASSphase (Toward Tough Glasses with Controlled Nanoscale Heterogeneities)
Période du rapport: 2020-10-01 au 2022-09-30
Specialty glass manufacturing is annually a €30 billion industry worldwide and transparent oxide glasses are one of the most important engineering and functional material families owing to their unique features, such as tailorable physical properties, formability, and relatively low cost. However, at the same time, intrinsic brittleness continues to be their main drawback, which severely restricts many applications. Therefore, improving the mechanical properties (such as crack initiation resistance, fracture toughness, hardness, etc.,) of glasses is also crucial for addressing major challenges in consumer electronics, energy, information technology and other wide industry areas.
Various extrinsic and intrinsic approaches have been attempted to improve the toughness of oxide glasses. Extrinsic techniques usually lead to a loss of transparency. In contrast, intrinsic techniques rely on the optimization of the inherent fracture resistance of the glass network by tuning their atomic structure or microstructure. The present study explored the possibility to improve the fracture toughness and damage resistance of oxide glasses through controlled nanoscale phase separation and crystallization. Ultimately such research could enable the design of tough, yet transparent oxide materials.
To achieve this aim, three specific objectives are included in the GLASSphase project:
(1) Enable prediction and control of the propensity for phase separation and the nano-domain size/composition
(2) Understand the effect of nanoscale phase separation on glass toughness and nanoductility
(3) Reveal the contribution of nanoductility to macroscopic crack propagation and fracture patterns.
The project has revealed the toughening mechanism induced by heterogeneous structures and its impact on macroscopic crack propagation. It thus suggests a new route to design glasses that are tough, yet transparent.
Various extrinsic and intrinsic approaches have been attempted to improve the toughness of oxide glasses. Extrinsic techniques usually lead to a loss of transparency. In contrast, intrinsic techniques rely on the optimization of the inherent fracture resistance of the glass network by tuning their atomic structure or microstructure. The present study explored the possibility to improve the fracture toughness and damage resistance of oxide glasses through controlled nanoscale phase separation and crystallization. Ultimately such research could enable the design of tough, yet transparent oxide materials.
To achieve this aim, three specific objectives are included in the GLASSphase project:
(1) Enable prediction and control of the propensity for phase separation and the nano-domain size/composition
(2) Understand the effect of nanoscale phase separation on glass toughness and nanoductility
(3) Reveal the contribution of nanoductility to macroscopic crack propagation and fracture patterns.
The project has revealed the toughening mechanism induced by heterogeneous structures and its impact on macroscopic crack propagation. It thus suggests a new route to design glasses that are tough, yet transparent.
1.The activities and results of the project
Scientific activities of the project:
(1) Scientific Training: The initial instrument (the instruments used for glass synthesis and mechanical properties characterization) training and structural characterization instruments training were performed.
(2) Synthesis of glasses, structural characterization, and control of micro-structure: In this project, four glass systems were designed and synthesized, one is amorphous phase-separated glass, and the other three are glass-ceramics research systems. The structure of homogeneous and nanoscale heterogeneities glasses were characterized. The nano-domains were controlled using different heat treatment parameters or tuning the composition.
(3) Mechanical property characterization: The mechanical properties mainly contained Young’s modulus, Poisson’s ratio, hardness, crack resistance, indentation toughness and fracture toughness.
According to the performed research in these subprojects, it has been found that when the nanoscale soft inclusions (separated phase) are in the glass matrix, a decrease in the size of nanoscale separation phase and increase in its fraction can help to improve the crack initiation resistance.In contrast, when nanoscale stiff inclusions (stiff crystals) are in glass matrix, they have a more pronounced effect on the mechanical properties improvement of the glass, especially for fracture toughness. In our research, we also made the important finding that a piezoelectric crystal as a secondary phase in the glass matrix can improve both crack initiation resistance and fracture toughness, which offer a new route to design transparent glass-ceramics with high damage-resistance and fracture toughness. It is worth mentioning that all the studied glass materials have improved mechanical properties while maintaining good transmittance by controlling the content and size of inclusions using heat treatment.
Non-scientific activities of the project:
(1) The management of the project: The career development and data management plans were submitted. Support received from the supervisor Prof. Smedskjaer and the administrative staff at the host institution has been very good and essential. Regular update meetings and presentations in group meeting were scheduled.
(2) Teaching and supervising training: Two Ph.D.-level courses and PBL teaching model were participated. After that, I co-supervised one group of master project students as well as one master thesis student to do some research about the mechanical properties of phase-separated glasses.
(3) Forging new networking and collaborative relationship: Worked with Prof. Mathieu Bauchy (UCLA, USA), Prof. Francisco Muñoz (CSIC, Spain), Prof. Lars R. Jensen (AAU, Denmark) and Dr. Randall E. Youngman (Corning, USA) on GLASSphase project. Besides, the Danish glass industry, such as Skamol and Rockwool International, were visited.
These activities enhanced my professional skills on mechanics of micro-structured oxide glass materials, improved my management and supervising skills as an independent scientist, established a strong collaboration network. All this will help me in my future glass research career.
2. Impact shared to the scientific community through different channels
(1) The work has been or is about to be published in peer-reviewed journals: (i) Influence of Phase Separation Microstructure on the Mechanical Properties of Transparent Modifier-Free Glasses (J. Non-Cryst. Solids, published); (ii) Mechanical Properties of Transparent Sodium Phosphosilicate Glass-Ceramics (submitted); (iii) Piezoelectric Crystal Phase Enables High Damage-Resistance and Damage-Tolerance in Transparent Glass Ceramics (in preparation); and (iv) Influence of Nano-Domain Properties on The Damage Resistance and Fracture Toughness of Phase-Separated Oxide Glasses (in preparation). These papers will be distributed to the community via email, LinkedIn, and Twitter, and will be available on AAU repository (VBN).
(2) The work was presented at the following two international conferences: (i) The International Year of Glass Symposium (Aalborg, 2022); and (ii) International Congress on Glass (Berlin, 2022).
(3) The project background and results have been presented on Prof. Smedskjaer’s group webpage.
Scientific activities of the project:
(1) Scientific Training: The initial instrument (the instruments used for glass synthesis and mechanical properties characterization) training and structural characterization instruments training were performed.
(2) Synthesis of glasses, structural characterization, and control of micro-structure: In this project, four glass systems were designed and synthesized, one is amorphous phase-separated glass, and the other three are glass-ceramics research systems. The structure of homogeneous and nanoscale heterogeneities glasses were characterized. The nano-domains were controlled using different heat treatment parameters or tuning the composition.
(3) Mechanical property characterization: The mechanical properties mainly contained Young’s modulus, Poisson’s ratio, hardness, crack resistance, indentation toughness and fracture toughness.
According to the performed research in these subprojects, it has been found that when the nanoscale soft inclusions (separated phase) are in the glass matrix, a decrease in the size of nanoscale separation phase and increase in its fraction can help to improve the crack initiation resistance.In contrast, when nanoscale stiff inclusions (stiff crystals) are in glass matrix, they have a more pronounced effect on the mechanical properties improvement of the glass, especially for fracture toughness. In our research, we also made the important finding that a piezoelectric crystal as a secondary phase in the glass matrix can improve both crack initiation resistance and fracture toughness, which offer a new route to design transparent glass-ceramics with high damage-resistance and fracture toughness. It is worth mentioning that all the studied glass materials have improved mechanical properties while maintaining good transmittance by controlling the content and size of inclusions using heat treatment.
Non-scientific activities of the project:
(1) The management of the project: The career development and data management plans were submitted. Support received from the supervisor Prof. Smedskjaer and the administrative staff at the host institution has been very good and essential. Regular update meetings and presentations in group meeting were scheduled.
(2) Teaching and supervising training: Two Ph.D.-level courses and PBL teaching model were participated. After that, I co-supervised one group of master project students as well as one master thesis student to do some research about the mechanical properties of phase-separated glasses.
(3) Forging new networking and collaborative relationship: Worked with Prof. Mathieu Bauchy (UCLA, USA), Prof. Francisco Muñoz (CSIC, Spain), Prof. Lars R. Jensen (AAU, Denmark) and Dr. Randall E. Youngman (Corning, USA) on GLASSphase project. Besides, the Danish glass industry, such as Skamol and Rockwool International, were visited.
These activities enhanced my professional skills on mechanics of micro-structured oxide glass materials, improved my management and supervising skills as an independent scientist, established a strong collaboration network. All this will help me in my future glass research career.
2. Impact shared to the scientific community through different channels
(1) The work has been or is about to be published in peer-reviewed journals: (i) Influence of Phase Separation Microstructure on the Mechanical Properties of Transparent Modifier-Free Glasses (J. Non-Cryst. Solids, published); (ii) Mechanical Properties of Transparent Sodium Phosphosilicate Glass-Ceramics (submitted); (iii) Piezoelectric Crystal Phase Enables High Damage-Resistance and Damage-Tolerance in Transparent Glass Ceramics (in preparation); and (iv) Influence of Nano-Domain Properties on The Damage Resistance and Fracture Toughness of Phase-Separated Oxide Glasses (in preparation). These papers will be distributed to the community via email, LinkedIn, and Twitter, and will be available on AAU repository (VBN).
(2) The work was presented at the following two international conferences: (i) The International Year of Glass Symposium (Aalborg, 2022); and (ii) International Congress on Glass (Berlin, 2022).
(3) The project background and results have been presented on Prof. Smedskjaer’s group webpage.
The present study seeks a new route to design glasses with higher toughness, i.e. ability to absorb energy and plastically deform without fracture by controlled phase separation or nanoscale crystals in glass matrix. Such research elucidates the influence of nanoscale heterogeneity induced by controlled phase separation on the fracture toughness and damage resistance of oxide glasses, solves the difficult problem of simultaneously improving the resistances to crack initiation and growth, which will facilitate the future design of transparent, yet highly damage-resistant and damage-tolerant glass ceramics. Furthermore, through the visits to Skamol and Rockwool International, the collaboration with Corning, and the presentation in International Congress on Glass, the research results are communicated to the Danish glass industry and international glass industry. The GLASSphase project provides guidelines toward developing high-toughness, yet transparent micro-structured glass, and provides knowledge and technology to solve bottlenecks in glass applications, which will benefit a wider range of glass applications.