Path Calculation of 7-axes Synchronous Quasi-Tangential Laser Manufacturing

Quasi-tangential laser processing, also called laser turning is increasingly applied for various applications. Specifically, its ability to generate complex geometries with small feature sizes at high precision and surface quality in hard, brittle and electrically non-conductive materials. Due to the geometric flexibility, the process is well suited for prototyping in hard-to-machine materials such as ceramics, carbides and super-abrasives. However, the lack of advanced software solutions for this novel process hitherto limited the exploitation of the potential. Here, we discuss a unique computer aided manufacturing approach for synchronous 7-axis laser manufacturing with quasi-tangential strategies. This gives the peerless possibility to process arbitrary geometries, which cannot be manufactured with conventional techniques. A detailed description of the path calculation with derivation and procedures is given. The generated machine code is tested on a 7-axis laser manufacturing setup. Following, a processed cylindrical ceramic specimen with a continuously varying profile along a helical path is presented. The profile is constituted by a rectangular over half-spherical to a triangular groove with defined pitch, which provides the validation of this CAM solution. Measurements of the produced specimen show high adherence with the target geometry with an average deviation below 10 µm.

Effect of Low Temperature Sintering on the Porosity and Microstructure of Porous Zeolite Ceramic

Manufacturing a porous ceramic specimen from natural zeolite materials mined in Malang, Indonesia was conducted by using a low temperature sintering. In this study, a porous ceramic property with rectangular shaped and prism shaped fillets at each end were sintered at 800-900°C and finally were investigated. Density and porosity measurements were performed using Archimedes method. The microstructure photos were used to measure the neck diameter and the contact angle between the two grains particles and two-dimensional porosity. The result of the zeolite ceramic measurement shows that the higher the sintering temperature the higher the density value and the smaller the open porosity. While from the microstructure photo it is shown that the neck diameter was larger the contact angle was wider. This phenomenon was happened because of the flux diffusion on the grain boundaries. This diffusion flow condition would influence the specimen surface, volume and grain boundary so that the porous ceramic density increases.

In Situ Measurements of Raman Spectra for PLZT Ceramics under Compressive Stresses

A lanthanum doped lead zirconate titanate (PLZT) ceramic specimen was prepared by the conventional solid state reaction method. The crystal phase and morphology of the PLZT specimen were characterized by XRD and SEM techniques, with the hysteresis loop by RT6000HVS system. The compressive stress was applied to the PLZT specimen through the microtest mechanical loading device. In-situ Raman spectra focused on a fixed grain under various compressive stresses were recorded for different polarization directions of the scattered light. The effects of stresses on the Raman spectra and the intensity ratio between the E+B1 and E(2TO) modes are discussed.

Qualitative Assessment of Wear Resistance and Surface Hardness of Different Commercially Available Dental Porcelain: An in vitro Study

ABSTRACT Introduction In an attempt to minimize wear damage to the enamel of antagonist teeth, new low and medium fusing ceramic materials have been developed. Manufacturers usually claim that these ceramics are wear-friendly because of their lower hardness, lower concentrations of crystal phase, and smaller crystal sizes. This study aimed to quantitatively analyze the wear strength of various commercially available dental porcelain with tooth enamel as well as the surface hardness of these dental porcelain. Materials and methods The basic model was designed as a pin on plate arrangement. The tooth specimens were mounted on the stylus which was centered on the ceramic specimen in a wear testing machine. The dental ceramic specimen was centered in the metal die. A load of 40 N was applied at a rate of 80 cycles/minute for 15 minutes. In the current study, mean wear depth (Ra) value, volumetric loss, and surface hardness were obtained by standard quantification method and were statistically evaluated. Results Ceramco-3 was reported to be most abrasive for enamel; however, Duceram love significantly more abraded itself than the other two, Ceramco-3 and Vita Alpha, and generated the lowest loss of enamel. Also, same abrasive type of wear was revealed for all three variants of tested ceramics. Conclusion Ceramco-3 was the most abrasive for enamel, while surface roughness (mean wear depth) of Duceram love was maximum and for Ceramco-3 it was minimum. The value of surface roughness for Vita Alpha was in between Duceram love and Ceramco-3. Nonetheless, the mean surface hardness of Duceram love was found to be least and maximum for Vita Alpha. Clinical significance In situations of dental wear and wasting tooth disease (Attrition/Abrasion), Duceram can be applied in lieu of Ceramco-3 so as to prevent worsening of existing dentition. However, in younger patients Vita Alpha would offer maximum durability due to its greater surface hardness. How to cite this article Singh A, Nagpal A, Pawah S, Pathak C, Issar G, Sharma P. Qualitative Assessment of Wear Resistance and Surface Hardness of Different Commercially Available Dental Porcelain: An in vitro Study. J Contemp Dent Pract 2016; 17(9):755-761.

Effect of H3BO3 Coating on the Microwave Dielectric Properties of BZN Ceramics

(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7(BZN) ceramic samples were prepared by solid state reaction. B2O3 was introduced by liquid coating technology with H3BO3 solution in the BZN ceramic specimen to reduce its sintering temperature. The sintering behavior, phase composition and dielectric properties of ceramics were investigated by X-ray diffraction, scanning electron microscopy and vector network analyzer. The (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 ceramic composite could be sintered well at 900°C for 3h when 0.9M/l H3BO3 was added and showed good dielectric properties of εr=150,Q×f=228,τf=-362ppm/°C.

Tribology research of the turned zirconium-dioxide ceramics

The zirconium dioxide as basic material is suitable to machine by tool with regular edge derivingfrom lower ceramic hardness and from other characteristics so in case of piece production or small – andmedium series production, at quick prototype production can become potential material alike. The aims tocompare the arising frictional characteristics in case of dry friction condition in case of ceramic – steelsurface pairs machined with different sets. We have developed for an equipment to carry out tribologicaltests. During the test we pressure the steel counter face with determined normal direction force thecasing surface of the rotating ceramic specimen and in the meantime we measure the value of the frictionforce with force meter cell. We have calculated the friction coefficient characterizing the system from thenormal direction force and the friction force as well as we measured the wear of the steel specimen andits deformation.