Browsing by Author "Sajadi, Seyed Mohammad"

Now showing 1 - 8 of 8
  • Thumbnail Image
    Item
    Additive manufacture-assisted method for making structural elements having controlled failure characteristics
    (2023-08-15) Sajadi, Seyed Mohammad; Meiyazhagan, Ashokkumar; Boul, Peter; Rahman, Muhammad; Thaemlitz, Carl; Ajayan, Pulickel; Rice University; Saudi Arabian Oil Company; William Marsh Rice University; United States Patent and Trademark Office
    A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.
  • Thumbnail Image
    Item
    Additive manufacture-assisted method for making structural elements having controlled failure characteristics
    (2024-06-18) Sajadi, Seyed Mohammad; Meiyazhagan, Ashok Kumar; Boul, Peter; Rahman, Muhammad; Thaemlitz, Carl; Ajayan, Pulickel; Rice University; Saudi Arabian Oil Company; United States Patent and Trademark Office
    A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.
  • Thumbnail Image
    Item
    Additive manufacture-assisted method for making structural elements having controlled failure characteristics
    (2024-05-28) Sajadi, Seyed Mohammad; Meiyazhagan, Ashok Kumar; Boul, Peter; Rahman, Muhammad; Thaemlitz, Carl; Ajayan, Pulickel; Rice University; Saudi Arabian Oil Company; United States Patent and Trademark Office
    A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.
  • Thumbnail Image
    Item
    Additive manufacture-assisted method for making structural elements having controlled failure characteristics
    (2024-05-28) Sajadi, Seyed Mohammad; Meiyazhagan, Ashok Kumar; Boul, Peter; Rahman, Muhammad; Thaemlitz, Carl; Ajayan, Pulickel; Rice University; Saudi Arabian Oil Company; United States Patent and Trademark Office
    A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.
  • Thumbnail Image
    Item
    Cement-based direct ink for 3D printing of complex architected structures
    (2021-02-09) Rahman, Muhammad M.; Sajadi, Seyed Mohammad; Kumar, Ashok; Boul, Peter J.; Thaemlitz, Carl; Ajayan, Pulickel M.; Rice University; Saudi Arabian Oil Company, Dhahran (SA); United States Patent and Trademark Office
    Provide is a cement ink for a cement ink for 3D printing (which also includes additive manufacturing) of 3D cement structures and materials. The cement ink includes an American Petroleum Institute (API) Class G cement, a nano-clay, a superplasticizer, a hydroxyethyl cellulose, and a defoamer. The nano-clay may be hydrophilic bentonite. The superplasticizer may be a polycarboxylate ether. The defoamer may be 2-ethyl-1-hexanol. Processes for forming the cement ink and printing 3D cement structures using the cement ink are also provided.
  • Thumbnail Image
    Item
    Damage-tolerant 3D-printed ceramics via conformal coating
    (AAAS, 2021) Sajadi, Seyed Mohammad; Vásárhelyi, Lívia; Mousavi, Reza; Rahmati, Amir Hossein; Kónya, Zoltán; Kukovecz, Ákos; Arif, Taib; Filleter, Tobin; Vajtai, Robert; Boul, Peter; Pang, Zhenqian; Li, Teng; Tiwary, Chandra Sekhar; Rahman, Muhammad M.; Ajayan, Pulickel M.
    Ceramic materials, despite their high strength and modulus, are limited in many structural applications due to inherent brittleness and low toughness. Nevertheless, ceramic-based structures, in nature, overcome this limitation using bottom-up complex hierarchical assembly of hard ceramic and soft polymer, where ceramics are packaged with tiny fraction of polymers in an internalized fashion. Here, we propose a far simpler approach of entirely externalizing the soft phase via conformal polymer coating over architected ceramic structures, leading to damage tolerance. Architected structures are printed using silica-filled preceramic polymer, pyrolyzed to stabilize the ceramic scaffolds, and then dip-coated conformally with a thin, flexible epoxy polymer. The polymer-coated architected structures show multifold improvement in compressive strength and toughness while resisting catastrophic failure through a considerable delay of the damage propagation. This surface modification approach allows a simple strategy to build complex ceramic parts that are far more damage-tolerant than their traditional counterparts. Conformal polymer coating leads to damage-tolerant architected ceramic structures with high strength and toughness. Conformal polymer coating leads to damage-tolerant architected ceramic structures with high strength and toughness.
  • Thumbnail Image
    Item
    Direct 3D Printing of Complex Materials
    (2022-04-27) Sajadi, Seyed Mohammad; Ajayan, Pulickel M.
    Additive manufacturing (AM) uses a data computer-aided-design (CAD) model to direct hardware to deposit material, layer upon layer, in precise geometric shapes. As its name implies, additive manufacturing adds material to create an object. By contrast, it is often required to remove material through milling, machining, or other processes in conventional fabrication. AM technology presents exceptional openings to design and build complex structures that are unattainable under conventional manufacturing constraints. AM processes are known mainly by 3D printing also promote the realization of engineered materials with microstructures and properties that are impossible via traditional synthesis procedures. Overall, this thesis scope explores the fabrication of complex structures with exceptional mechanical properties through 3D printing and examines new techniques for printing different materials, including cement, graphite, and copper. The second chapter of this thesis presents several high-performance ultralight polymer-based structures that can only fabricate through AM technology. In addition, this chapter discusses the role of geometry in the mechanical properties of printed structures. Despite their high strength and modulus, ceramic and cementitious materials are limited in many structural applications due to inherent brittleness and low toughness. The third chapter describes a straightforward approach to enhance the fracture toughness of brittle materials, including ceramic and cement. Chapter fourth describes the development of a nano-clay modified cement-based direct ink that enables high-resolution 3D printing of complex architected structures of tunable geometries, which could alleviate the fracture toughness of cement structures. The fifth chapter reports the development of colloidal graphite ink from commercial graphite powders that allows the fabrication of any complex architectures with tunable geometry and directionality via 3D printing at room temperature. The direct ink printing of complex 3D architectures of graphite without further heat treatments could lead to easy shape engineering and related graphite applications at various length scales, including complex graphite molds or crucibles. The sixth chapter demonstrates the possibilities of printing various metals and dissimilar materials interfaces using direct ink writing (DIW) aided 3D printing via a unique binder, namely clay. Several structures such as copper, copper/graphite, and copper/iron hetero-structures are developed using DIW, with desirable mechanical properties. The printing process and post-sintering have been done in succession to obtain complex architecture from metals and dissimilar metal-metal, metal-nonmetal interfaces. The technique allows enormous flexibility in multi-material printing, leading to various applications involving hetero-interfaces between different materials. The overall significance of the original collective work described here, and future directions are suggested at the end of this thesis.
  • Thumbnail Image
    Item
    Direct ink printing of multi-material composite structures
    (2024-01-02) Sajadi, Seyed Mohammad; Boul, Peter; Tiwary, Chandra Sekhar; Rahman, Muhammad M.; Ajayan, Pulickel M.; Thaemltiz, Carl; William Marsh Rice University; Saudi Arabian Oil Company; United States Patent and Trademark Office
    Methods for fabricating a multi-material composite structure are described. Methods for fabricating a multi-material composite structure include forming a first colloidal ink solution with a first material matrix, water, and a rheology modifying agent; forming a second colloidal ink solution with a second material matrix, water, and a rheology modifying agent; printing a first layer on a substrate using a first printing nozzle carrying the first colloidal ink solution; printing a second layer on top of the first layer using a second printing nozzle carrying the second colloidal ink solution; forming a 3D structure by printing a plurality of layers including the first layer and the second layer printed in an alternating pattern; and sintering the 3D structure to form the multi-material composite structure.