A Systematic Study on Impact of Binder Formulation on Green Body Strength of Vat-Photopolymerisation 3D Printed Silica Ceramics Used in Investment Casting

Abstract

Additive ceramics manufacturing with vat-photopolymerisation (VP) is a developing field, and the need for suitable printing materials hinders its fast growth. Binder mixtures significantly influence the mechanical properties of printed ceramic bodies by VP, considering their rheological properties, curing performances and green body characteristics. Improving mechanical characteristics and reducing cracks during printing and post-processes is mainly related to binder formulations. The study aims to develop a binder formulation to provide the printed ceramic specimens with additional green strength. The impact on mechanical properties (ultimate tensile strength, flexural strength, Young’s and strain at breakpoint), viscosity and cure performance of Urethane Acrylate (UA) and thermoplastic Polyether Acrylate (PEA) oligomers to monofunctional N-Vinylpyrrolidone (NVP), 1,6-Hexanediol Diacrylate (HDDA) and Tri-functional Photocentric 34 (PC34) monomers were investigated under varying concentrations. The best mechanical characteristic was showcased when the PC34 was replaced with 20–30 wt.% of UA in the organic medium. The Thermogravimetric Analysis (TGA) and sintering test outcomes revealed that increasing the content of NVP in the organic medium (above 15 wt.%) leads to uncontrolled thermal degradation during debinding and defects on ceramic parts after sintering. The negative effect of UA on the viscosity of ceramic-loaded mixtures was controlled by eliminating the PC34 compound with NVP and HDDA, and optimum mechanical properties were achieved at 15 wt.% of NVP and 65 wt.% of HDDA. PEA is added to provide additional flexibility to the ceramic parts. It was found that strain and other mechanical parameters peaked at 15 wt.% of PEA. The study formulated the most suitable binder formulation on the green body strength of printing silica ceramics as 50 wt.% HDDA, 20 wt.% Urethane Acrylate, 15 wt.% NVP and 15 wt.% PEA.

Recycled PET Composites Reinforced with Stainless Steel Lattice Structures Made by AM

“…Recycled PET material was subjected to a serious selection process to remove labels and caps, as well as sorting according to the color. The viable material was ground twice until flakes of 0.2-10 mm were obtained with a relative density of 1.22 g/cm 3 . The resulting recycled PET powder was properly conditioned through washing procedures, including boiling in a sodium hydroxide solution to remove oil and fat traces, and then it was thoroughly cleaned and dried.…”

“…Additive manufacturing gains a lot of advantages regarding the newest technologies due to its ability to generate complex structures from various materials such as polymers [1,2], ceramics [3,4] and metals [5,6], adding layer over layer during the printing process. This new technology is suitable for complex geometry [7,8] that would be very difficult for conventional casting or mechanical cutting [9].…”

Synthesis of Room Temperature Curable Polymer Binder Mixed with Polymethyl Methacrylate and Urethane Acrylate for High-Strength and Improved Transparency

“…An optimized polymer binder was prepared by adjusting the PMMA to UA ratio while the content of the initiator and reaction promoting catalyst was fixed. In future studies, it will be mixed with luminescent paint and used as a promising photo-stimulation smart, sensitive material [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58].…”