Microstructure and Mechanical Properties of TiC/TiB Composite Ceramic Coatings In-Situ Synthesized by Ultrasonic Vibration-Assisted Laser Cladding

Laser cladding coating has many advantages in surface modification, such as a small heat-affected zone, and good metallurgical bonding. However, some serious problems such as pores, and poor forming quality still exist in the coating. To suppress these problems, a novel process of ultrasonic vibration-assisted laser cladding process was adopted to in-situ synthesize TiC/TiB composite ceramic coating on the surface of titanium alloy. Results showed that the introduction of ultrasonic vibration effectively improved the surface topography of the coating, reduced the number of pores in the coating, refined the crystal grains of the coating, decreased the residual tensile stress in the coating, and increased the micro-hardness of the coating. The tribological properties of the coating were significantly improved by the ultrasonic vibration, the wear resistance of the coating fabricated with ultrasonic vibration at power of 400 W increased about 1.2 times compared with the coating fabricated without ultrasonic vibration, and the friction coefficient decreased by 50%.

Special Device for Diamond Grinding of the Backup Surfaces and Perimeter of Articles from Nonmetallic Ceramic Materials

In developed countries, material scientists are working intensively to create high-strength (metallic) technical ceramics. If such a material is created, it will be possible to manufacture such parts of power units (transmissions) of cars as shafts, turbines, etc. In the future, the latest composite ceramic materials with unique properties will gradually replace metals in the production of machine parts. Special device for diamond grinding of articles from composite, non-metallic, brittle materials (technical ceramics on the base of SiC, Al2O3; polycrystalline diamond, composite – Si + SiC + diamond etc.) is a universal flat grinding machine that enables to grind with high productivity both supporting main surfaces and lateral side surfaces – perimeter of an article of prismatic shape. It is also possible to grind substrates of other configurations – round, oval, etc. Grinding depending on sizes of articles can be done of both single and group of articles. The grinding takes place by the means of spring feeding of the article by pneumatic system that enables to prevent breakage of articles from brittle non-metallic materials in process of machining and obtain maximum high quality of the machined surface.

Diamond Grinding Technology of Flexural Strength Test Pieces of Super hard, Brittle, Composite-ceramic Materials and Technological Equipment

At the present stage of the revolutionary development of technologies, scientists from the leading countries of the world are working intensively to create qualitatively new materials whose physical-mechanical, electrical, thermal or other properties far exceed the basic constructions, armament or other metals used. Such materials are surface, brittle, composite ceramic materials (based on oxide and carbide ceramics, state-of-the-art surface compositions, polycrystalline diamond + Si  SiC and etc.). A progressive process for diamond grinding test samples from composite ceramic materials to determine the bending strength is discussed. The proposed technological process is based on an original and effective method for polishing the flat surfaces of articles made of difficult-to-process and composite materials - low-temperature precision grinding (LPG). Based on the results of many years and multilateral studies in the field of diamond processing of various non-metallic, composite and ceramic materials, optimum conditions for diamond polishing of mentioned materials have been determined and recommended. Technological equipment and equipment for processing composite and ceramic materials are also disclosed.

Comparison of Silane Heat Treatment by Laser and Various Surface Treatments on Microtensile Bond Strength of Composite Resin/Lithium Disilicate

In the current study, we evaluated the effects of heat treatment (by Er:YAG or furnace) and various surface treatments on the microtensile bond strength (μTBS) of silanized lithium disilicate ceramic. Seventy lithium disilicate (IPS e. max Press; Ivoclar Vivadent) and composite resin (Tetric N-Ceram; Ivoclar Vivadent) blocks were made and distributed into seven groups (n = 10) at random: S: silanization alone; ALS: airborne particle abrasion (APA) and silanization; SC: APA modified with silica and silanization; SHT1: silanization and heat treatment by Er:YAG; SHT2: silanization and heat treatment performed in the furnace (100 °C, 1 min); HF: etching with HF; and HFS: etching with HF and silanization. Every ceramic specimen was cemented to a composite resin block after surface treatment. Cemented specimens were embedded into acrylic resin and were tested with the μTBS test. Data were analyzed using one-way ANOVA and Tamhane T2 tests (α = 0.05). The SHT1 group had the highest bond of strength compared to the other groups (27.46 MPa). The ALS group had the lowest strength of the groups (15.56 MPa). Between SHT2 and HFS (p = 1), the comparison of the mean µTBS values showed no significant differences. It was concluded that silane heat treatment increased the resin composite–ceramic bond strength; however, within the terms of μTBS, the Er:YAG laser treatment was more successful than other surface treatment applications.

The Effect of α-Al2O3 Composite on Energy Storage Characteristics of the Orthogonal Phase PLZST Antiferroelectric Ceramics

The effect of (1-x)(Pb0.97La0.02)(Zr0.675Sn0.285Ti0.04)O3-xAl2O3, with x=0~0.04, 0.08, 0.10 composite ceramic samples was studied. In this experiment, the PLZST powder was pre-fired to obtain the perovskite structure, and then combined with α-Al2O3 to increase the BDS of the ceramic. The test results show that the composite thick film samples are all perovskite orthorhombic phases, and Al2O3 is mainly filled in the grain gaps with a flaky structure. A proper content of composite Al2O3 can increase the density of ceramics. With x=0.02, the maximum value of BDS is 25.27 kV/mm, which is 60% higher than pure PLZST material, and the releasable energy storage density also reaches a maximum of 2.95 J/cm³. After the composite amount exceeds 0.03, the saturation polarization intensity decreases significantly. The energy storage efficiency of each sample is generally not high, all of which are less than 65%.

Surface Characterisation of Dental Resin Composites Related to Conditioning and Finishing

Due to the little information related to surface processing and conditioning of resin matrix ceramic materials previous glazing, the main purpose of this in vitro study was to investigate the effect of different surface treatments on the surface morphology of different resin composite materials. Five types of resin composite CAD-CAM materials: a resin composite ceramic Vita Enamic (E) and four types of nanoparticle-filled resins, like Lava Ultimate (L), Cerasmart (C), Shofu HC (S), Hyramic (H) were taken into consideration. Specimens received the following surface treatment protocols: conventional polishing [p], polishing and glazing [pg], conditioning with CoJet [c], conditioning with CoJet and glazing [cg], sandblasting [s], sandblasting and glazing [sg], etching [e], etching and glazing [eg]. Surface roughness was analyzed for all samples and nanosurface topographic characterization was made by Atomic Force Microscopy. The highest roughness was registered for sandblasted surfaces [s], followed by tribochemical silica airborne particle abrasion [c], and etching [e]. A very strong correlated conditioning behavior of resin nanoceramic materials, like L, C and S samples was found. The microroughness decreased thus [s] > [c] > [e]. These are moderate correlated with H, and are moderate negative correlated to E, where e is more efficient. Three-dimensional images indicated visible grain boundaries after conditioning, for all materials. After polishing and glazing, surfaces became smoother. For all tested conditioning and finishing methods, surface roughness values were within clinically acceptable limits. Finishing by polishing was proved to be a good choice for all materials taken into consideration, polishing and glazing likewise, excepting Hyramic. For Enamic and Shofu HC sandblasting or tribochemical conditioning and glazing and for Hyramic polishing and glazing are not the best options, related to nanoroughness values. Referring to the nanosurface topography, for Enamic, Cerasmart and Hyramic, glazing would be the method of choice, associated with the adequate conditioning method for each material.