scholarly journals Highly Flexible and Photo-Activating Acryl-Polyurethane for 3D Steric Architectures

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 844
Author(s):  
Ji-Hong Bae ◽  
Jong Chan Won ◽  
Won Bin Lim ◽  
Ju Hong Lee ◽  
Jin Gyu Min ◽  
...  
Keyword(s):  
High Surface ◽  
3D Structure ◽  
Surface Hardness ◽  
Uv Absorbance ◽  
Mass Ratio ◽  
Digital Light Processing ◽  
Methylene Diphenyl Diisocyanate ◽  
High Elasticity ◽  
Flexible Applications ◽  
Exposure Energy

An acryl-functionalized polyurethane (PU) series was successfully synthesized using poly(tetramethylene ether) glycol-methylene diphenyl diisocyanate (PTMG-MDI) oligomer based on urethane methacrylates to control the flexibility of photo-cured 3D printing architectures. The mass ratio of acryl-urethane prepolymer: 1,4-butanediol (BD) chain-extender: diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiator was 10:0.25:1. To produce suitably hard and precisely curved 3D architectures, the optimal UV absorbance and exposure energy of the acryl-PTMG-MDI resin were controlled precisely. Owing to the optimized viscosity of the acryl-PTMG-MDI resins, they could be printed readily by digital light processing (DLP) to form precisely curved 3D architectures after mixing with 1,6-hexanediol diacrylate (HDDA). The acryl-PTMG-MDI formulations showed much better flexural resolution than the neat resins. The printed 3D structure exhibited high surface hardness, good mechanical strength, and high elasticity for flexible applications in consumer/industrial and biomedical fields.

NITRODUR 8524

Alloy Digest ◽  
2017 ◽  
Vol 66 (12) ◽  
Keyword(s):  
Fracture Toughness ◽  
Fatigue Strength ◽  
Tensile Properties ◽  
High Temperatures ◽  
High Surface ◽  
Surface Hardness ◽  
Operating Temperatures

Abstract NITRODUR 8524 (8CrMo16, 1.8524) is one of the Nitrodur family of nitriding steels that are used where high surface hardness and good fatigue strength are required and the material is also subjected to high temperatures. Nitrided surfaces maintain their hardness and strength at operating temperatures of up to approximately 500–550 deg C (932–1022 deg F). This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness. It also includes information on surface qualities as well as casting and forming. Filing Code: SA-807. Producer or source: Schmolz + Bickenbach Group.

DEUTSCHE EDELSTAHLWERKE CRYODUR 2067

Alloy Digest ◽  
2020 ◽  
Vol 69 (2) ◽  
Keyword(s):  
Cold Work ◽  
High Surface ◽  
Surface Hardness ◽  
Heat Treating ◽  
Chromium Alloy ◽  
Dimensional Changes ◽  
Short Run ◽  
Quench Hardening ◽  
Specialty Steel ◽  
Cold Work Tool Steel

Abstract Deutsche Edelstahlwerke Cryodur 2067 is a high-carbon, 1.5% chromium, alloy cold-work tool steel. In view of its higher hardenability than that of the non-alloy, water-hardening, cold work tool steels, this steel can be oil quenched, a factor that minimizes dimensional changes during quench hardening. Cryodur 2067 is suitable for short run tooling in applications requiring high surface hardness. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-786. Producer or source: Deutsche Edelstahlwerke Specialty Steel.

scholarly journals Interlocking birch plywood structures

2021 ◽  
pp. 095605992110222
Author(s):  
Chrysl A Aranha ◽  
Markus Hudert ◽  
Gerhard Fink
Keyword(s):  
High Surface ◽  
Surface Hardness ◽  
Experimental Tests ◽  
Digital Fabrication ◽  
Element Model ◽  
Component Level ◽  
Geometrical Properties ◽  
Stiffness Properties ◽  
The Face ◽  
Strength And Stiffness

Interlocking Particle Structures (IPS) are geometrically stable assemblies, usually fabricated from plate type elements that are interconnected by slotted joints. IPS are demountable and their components have the potential to be used and reused in different structures and configurations. This paper explores the applicability of birch plywood panels, which are characterized by a high surface hardness, for this type of structural system. Experimental tests were conducted to determine the mechanical properties of birch plywood plates. Moreover, IPS connections with different geometrical properties were investigated for two different load exposures: bending and rotation. The characteristics under bending exposure are influenced by the orientation of the face-veneers. For the rotational load exposure, very small strength and stiffness properties have been identified. A linear elastic finite element model is presented that shows a wide agreement with the test results. The study serves as an initial probe into the performance of IPS structures at the component level. Various aspects that are relevant for the design of IPS, such as the assembly, the accuracy and challenges regarding digital fabrication, the durability, and the structural performance are discussed.

scholarly journals Biofabrication of Cell-Laden Gelatin Methacryloyl Hydrogels with Incorporation of Silanized Hydroxyapatite by Visible Light Projection

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2354
Author(s):  
Jimmy Jiun-Ming Su ◽  
Chih-Hsin Lin ◽  
Hsuan Chen ◽  
Shyh-Yuan Lee ◽  
Yuan-Min Lin
Keyword(s):  
Mechanical Properties ◽  
Visible Light ◽  
3D Structure ◽  
Three Dimensional ◽  
3D Cell Culture ◽  
Composite Hydrogel ◽  
Digital Light Processing ◽  
Mg63 Cells ◽  
Marrow Mesenchymal Stem Cells ◽  
Low Cytotoxicity

Gelatin methacryloyl (GelMA) hydrogel is a photopolymerizable biomaterial widely used for three-dimensional (3D) cell culture due to its high biocompatibility. However, the drawback of GelMA hydrogel is its poor mechanical properties, which may compromise the feasibility of biofabrication techniques. In this study, a cell-laden GelMA composite hydrogel with a combination incorporating silanized hydroxyapatite (Si-HAp) and a simple and harmless visible light crosslinking system for this hydrogel were developed. The incorporation of Si-HAp into the GelMA hydrogel enhanced the mechanical properties of the composite hydrogel. Moreover, the composite hydrogel exhibited low cytotoxicity and promoted the osteogenic gene expression of embedded MG63 cells and Human bone marrow mesenchymal stem cells (hBMSCs). We also established a maskless lithographic method to fabricate a defined 3D structure under visible light by using a digital light processing projector, and the incorporation of Si-HAp increased the resolution of photolithographic hydrogels. The GelMA-Si-HAp composite hydrogel system can serve as an effective biomaterial in bone regeneration.

Surface Hardness Modify and Improve Wear Properties of EP\ NanoZrO2

2021 ◽  
Vol 19 (2) ◽  
pp. 77-82
Author(s):  
Fadhil K. Farhan ◽  
Aws Abbas Hussein ◽  
Ali Q. Tuama
Keyword(s):  
Wear Resistance ◽  
High Surface ◽  
Ceramic Powder ◽  
High Surface Area ◽  
Surface Hardness ◽  
Weight Ratio ◽  
Hardness Test ◽  
Wear Properties ◽  
Mechanical Mixing ◽  
Dioxide Powder

The liquid and mechanical mixing method was used in addition to ultrasound technology to prepare samples according to standard conditions. The percentage of cementing with ceramic powder was adopted from 1% to 4% as a weight ratio, and by using mixing drivers, nanocomposites were prepared depending on the theoretical density of the components. The velvet density was measured using Archimedes' method, and the results showed a successive improvement and increase in density with the weight ratio of addition. The results of the particulate hardness test showed a significant improvement in the results of the prepared nanostructures compared to the base sample (pure epoxy). With regard to the properties of wear resistance (wear modulus) using the screw-on-disk method, the cemented samples showed a higher wear resistance compared to the base sample. The results were interpreted based on the values of density and hardness in addition to the properties possessed by the ceramic powder of high surface area and average granular size of 32 nanometers through scanning electron microscopy. In this work, nanostructures based on (a polymer) supported with nanoscale zirconium dioxide powder were developed.

Increasing Hardness of Surface Layer of Low-Carbon Steel by Account of Plasma Treatment of Coating Modification

2021 ◽  
Vol 316 ◽  
pp. 794-802
Author(s):  
Andrey E. Balanovsky ◽  
Van Trieu Nguyen
Keyword(s):  
Surface Layer ◽  
Thermal Treatment ◽  
Plasma Treatment ◽  
Plasma Heating ◽  
High Surface ◽  
Surface Hardness ◽  
High Hardness ◽  
Diffusion Region ◽  
Low Carbon ◽  
Wide Range

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

Tribological Properties of Polyoxymethylene Composites Against Aluminum

2003 ◽  
Vol 125 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Masaya Kurokawa ◽  
Yoshitaka Uchiyama ◽  
Tomoaki Iwai ◽  
Susumu Nagai
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
High Surface ◽  
Surface Hardness ◽  
Disk Surface ◽  
Optical Microscope ◽  
Transfer Film ◽  
The Other ◽  
The Coefficient Of Friction

Tribological properties of several kinds of polyoxymethylene (POM) composites were evaluated for the purpose of developing a polymeric tribomaterial especially suited for mating with aluminum parts having low surface hardness. POM composites containing small amounts of silicon carbide (SiC), POM/SiC; those containing a small amount of calcium octacosanonoate besides SiC, POM/SiC/Ca-OCA; and the one blended with 24 wt % of polytetrafluoroethylene, POM/PTFE(24); were injection-molded into pin specimens and their tribological properties were tested by means of a pin-on-disk type wear apparatus using an aluminum (A5056) mating disk in comparison with a 303 stainless steel (SUS303) disk. Evaluation was focused on observation of the sliding surfaces of the pin specimens and the mating disks by a scanning electron microscope and an optical microscope together with the measurement of surface roughness. In the case of mating against a SUS303 disk having high surface hardness, all pin specimens did not roughen the disk surfaces even after long time of rubbing. Only POM/PTFE(24) composite obviously made a transfer film on the disk surface, while the other composites made an extremely thin one on it. POM/SiC(0.1)/Ca-OCA(1) composite, containing SiC 0.1 wt. % and Ca-OCA 1 wt. %, was found to show the lowest coefficient of friction and the lowest wear rate forming extremely thin transfer film on the mating disk. On the other hand, against an A5056 disk which has lower surface hardness than that of SUS303 disk, unfilled POM and POM composites except POM/SiC(0.1)/Ca-OCA(1) composite roughened the disk surfaces. However, the sliding surface of the A5056 disk rubbed with POM/SiC(0.1)/Ca-OCA(1) composite was significantly smoother and that of the pin specimen was also quite smooth in comparison with other pin specimens. Further, when each POM composite was rubbed against the A5056 disk, formation of transfer film was not obvious on the disk surfaces. For POM/SiC(0.1)/Ca-OCA(1) composite, the wear rate was the lowest of all POM composites, and the coefficient of friction was as low level as 60 percent of that of unfilled POM, but slightly higher than that of POM/PTFE(24) composite. For POM/SiC(0.1)/Ca-OCA(1) composite, the nucleating effect of SiC and Ca-OCA, which accelerated the crystallization of POM during its injection molding to form a matrix containing fine spherulites, must have resulted in increasing the toughness of the matrix and lowering the wear rate. Also, the lubricant effect of Ca-OCA should have lowered the coefficient of friction of the same matrix for rubbing against aluminum mating disk. POM/SiC(0.1)/Ca-OCA(1) composite was concluded as an excellent tribomaterial for mating with aluminum parts.

On Failure Problem of Gears Made From Very High Strength Steel

2011 ◽  
Author(s):  
Aizoh Kubo
Keyword(s):  
Carrying Capacity ◽  
High Strength Steel ◽  
High Surface ◽  
Surface Hardness ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Edge Contact ◽  
Load Carrying ◽  
Tooth Form ◽  
Very High

Some typical examples of failure of gears made from very high strength steel are shown and its trigger and whose causes are discussed: Many of such failure are triggered by tooth side edge contact or tooth tip edge contact and meshing-in of the wear debris. The limit of validity of the traditional methods for load carrying capacity of gears exists in the fact that they are based on the theory of contact of tooth flanks that realize conjugate or almost conjugate action of gears. To be able to design reliable gears made from very high strength steel, a principle is shown that suggests a new method for tooth form modification and of longitudinal crowing modification to avoid such failure. Metallurgical problem of gear material and special heat treatment aiming high surface hardness is also discussed.

scholarly journals Porous cage-derived nanomaterial inks for direct and internal three-dimensional printing

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Tangi Aubert ◽  
Jen-Yu Huang ◽  
Kai Ma ◽  
Tobias Hanrath ◽  
Ulrich Wiesner
Keyword(s):  
3D Printing ◽  
Structural Control ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Processing Technique ◽  
Advanced Materials ◽  
Host Matrix ◽  
Digital Light Processing ◽  
Three Dimensional Printing

Abstract The convergence of 3D printing techniques and nanomaterials is generating a compelling opportunity space to create advanced materials with multiscale structural control and hierarchical functionalities. While most nanoparticles consist of a dense material, less attention has been payed to 3D printing of nanoparticles with intrinsic porosity. Here, we combine ultrasmall (about 10 nm) silica nanocages with digital light processing technique for the direct 3D printing of hierarchically porous parts with arbitrary shapes, as well as tunable internal structures and high surface area. Thanks to the versatile and orthogonal cage surface modifications, we show how this approach can be applied for the implementation and positioning of functionalities throughout 3D printed objects. Furthermore, taking advantage of the internal porosity of the printed parts, an internal printing approach is proposed for the localized deposition of a guest material within a host matrix, enabling complex 3D material designs.

AN INVESTIGATION OF THE INFLUENCE OF CLIMATIC FACTORS ON THE EROSIVE WEAR KINETICS OF POLYMER COATINGS

Tribologia ◽  
2016 ◽  
Vol 268 (4) ◽  
pp. 115-125
Author(s):  
Danuta KOTNAROWSKA ◽  
Andrzej KOTNAROWSKI
Keyword(s):  
Grain Size ◽  
Climatic Factors ◽  
High Surface ◽  
Surface Hardness ◽  
Surface Profile ◽  
Erosive Wear ◽  
Epoxy Coatings ◽  
Mean Grain Size ◽  
Resistance Decrease ◽  
20 Nm

The paper presents investigation results concerning the influence of the modification with nanoparticles of silica (of mean grain size 12 nm or 20 nm) or aluminium trioxide (20 nm) of the structure of epoxy coatings on their resistance to climatic factors and the action of erosive particles. Epoxy coatings aged in natural climatic conditions showed an erosive resistance decrease with ageing. The erosive resistance decrease was accompanied by a hardness decrease as well as surface roughness increase. The highest resistance to erosive wear after 3 years of ageing revealed coatings modified with aluminium trioxide nanoparticles, while the lowest one showed coatings modified with silica nanoparticles of 12 nm mean grain size. Nanocoatings modified with aluminium trioxide nanoparticles also had the highest resistance to ageing; which was proven by the lowest increase of Ra and Rz surface profile parameter values with time, as well as by a high surface hardness, which was higher than hardness of new unmodified coatings.

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