Laser Cladding Cermet Coatings on Niobium Substrate

Pure niobium substrates were coated using laser cladding method. Pure molybdenum, Yttria Stabilized Zirkonia (YSZ) and corundum (Al2O3) powders were used as coating materials. Coatings were deposited on specimens as seperate paths with 3÷10mm width and 40mm of length. Two different laser power 3kW and 4kW were tested during deposition. In order to assess the quality of the Mo-YSZ and Mo-Al2O3 coatings, the light microscopy, Scanning Electron Microscopy (SEM), chemical analysis (EDS) and Vickers hardness test investigation were performed. The surface roughness and wear volume were also measured. As a result of YSZ-Mo powder cladding on the Nb substrate the composite layers were obtained without cracks and porosity not exceeding 1 μm. In addition, an increase in hardness of about 450 HV0.5 was revealed. As a result of Al2O3-Mo powder cladding on the Nb substrate the composite layers with many voids and cracks were obtained for each of the cladding variants.

Effect of Shot Peening on the Evolution of Scale on T91 Steel Exposed to Steam

Shot peening can be an effective solution for the prevention or retardation of scale formation, and subsequent exfoliation, upon exposure of the inner tube to steam in coal-fired power plants. In this study, specimens of T91 tubes were shot peened and then exposed to 1-bar steam for 100–1000 h at 650 °C, and were then analyzed using Vickers hardness test and microscopic techniques OM, SEM, TEM, etc. The analysis indicates that the oxide scales are typically Fe2O3 on the topmost layer, Fe3O4 below, and a FeCr2O4 spinel on the bottom in both shot peening treated and untreated specimens. However, the oxide scale thicknesses of shot peened specimens are thinner, indicating that shot peened specimens have better oxidation resistance. In addition, numerous defects, such as voids and micro-cracks, were found in the untreated specimens, which are believed to cause exfoliation of the uppermost Fe2O3 layers of the specimens exposed to steam for 800 and 1000 h. By contrast, the shot peened specimens maintained a dense contact oxide scale with fewer defects.

Evolution of the Microstructure of a CuCr1Zr Alloy during Direct Heating by Electric Current

Round tensile test specimens of an age-hardened CuCr1Zr alloy were subjected to direct electrical current heating in a Gleeble thermal–mechanical simulator at 800 °C. The mechanical properties were monitored by the Vickers hardness test, and the changes in the grain structure were examined by light metallography. A quantitative analysis of the size and distribution of fine precipitates during annealing was carried out using transmission electron microscopy (TEM). The grain structure showed a gradient corresponding to the gradient of the temperature on the test piece. Annealing for 60 s at 800 °C resulted in a partially (~50%) recrystallized structure with new grains about 45 μm in diameter. In the as-delivered condition, TEM documented tiny (1 to 4 nm) coherent chromium precipitates inducing strain fields in the matrix. During overaging, the particles lost their coherence and gradually coarsened up to a mean diameter of 40 nm after 300 s at 800 °C. The coarsening kinetics obeys Lifshitz, Sloyzov, and Wagner’s theory.

Karakterisasi hasil quenching besi cor pada manufaktur roda gigi mesin tenun

The development of science and technology today has a significant influence on technological development and advances in the industrial world. Casting is a product manufacturing technique in which the metal is melted in a furnace and then poured into a mold cavity that is similar to the original form of the cast product to be made. One of the results or products produced from the casting method in this study is a weaving gear component. The gear serves as a short distance power transmission based on the rotation ratio from the main shaft to the drive shaft. This study purpose to determine the effect of the quenching process with oil cooling media on cast iron material. The testing results reveal that the composition test results in 3.18% carbon content, such that the components in this gear manufacturing are used in cast iron, which essentially has the characteristics of being heat-resistant and brittle. It is also necessary to use it as a way of producing materials feeling the continuous impact. The brittling effect of quenching oil heat treatment improves the quality of the materials. It is observed from the research findings that use the Vickers hardness test that the quenching heat treatment shows a substantial difference in score. The highest Vickers hardness test score with quenching oil materials achieving a score of 427.84 VHN is seen. The test exhibits the maximum value of 378.18 VHN in raw materials.Keywords: Cast iron, quenching, chemical composition, Vickers hardness.

Calibration Of Vickers Hardness Test PT.Tenaris Seamless Pipe Indonesia Jaya Cilegon Using Standar Blok

A calibration is an activity to determine the conventional validity of the appointment value of measuring instruments and measuring materials by comparing them to standard measurements that are traceable to national and international standards for measurement units and or international and certified reference materials. The calibration is generally a process of adjusting the output or indication of a measurement device to match the magnitude of the standard used in certain accuracy. The purpose of this paper is to find out the vickers hardness test calibration whether the machine running normally or there is a problem with the device. A case study was conducted in PT. Tenaris SPIJ, Cilegon, Indonesia. A vickers hardness testing in the case study has its own reference standard, namely ISO 6507-2: 2018 Metal material - Hardness Test Verification and Calibration of the test machine. The vickers hardness test equipment is a machine to conduct tests using a diamond pyramid with a plane angle of 136°, by means of an emphasis by an indentor that results in a trace or indentation on the surface of the test object. The vickers hardness testing is abbreviated as HV or HVN and also known as Diamond Pyramid Hardness Test (DPH). Result of calibration in the case study was found the repeatability value on vickers hardness testing machine of 32 HV 10 and the error value of ±3%.

Effect of Stress Fields on Acoustic Emission during Delayed Fracture of Glass

We investigated the effects of the stress field on acoustic emission (AE) during delayed fracture of glass. Delay fracture occurrence was controlled by the Vickers indentation load and kind of glass. Delayed fractures of glass were monitored by an AE method. After the Vickers hardness test, the glass surface was observed and its condition was compared with the AE signals. Characteristic AE signals were identified, and it was shown that the AE method is effective in measurements on the delayed fracture of glass.

Laboratory Evaluation of IPS-lithium Disilicate Orthodontic Brackets

The purpose of the study is to evaluate the microhardness and light transmission through new Emax brackets with two ceramic brackets commercially available in the markets. The brackets were divided into three groups: (1) E max brackets (IPS E-max press, Ivoclar, Germany), (2) Gemini clear brackets (Unitek, 3M, USA), and (3) discovery pearl ceramic brackets (Dentaurum, Germany). The Vickers hardness test was used to evaluate the hardness of the wings in addition the light transmission of three brackets types were tested through using an orthodontic light cure device and light meter. The hardness test of discovery pearl ceramic brackets and Gemini clear brackets gave significantly higher than E.max one while later gave significantly more light transmission through it when compared with another two brackets. In conclusion, the noticeable tested brackets make E max material one of choice for modern esthetic brackets in future although the hardness is less comparing the other tested brackets due to the purity of material compering with other test brackets which are reinforced of their material, the new material requiring improving of mechanical performances.

MECHANICAL PROPERTIES OF PRODUCT FROM 7075 ALUMINUM CHIPS AFTER CONSOLIDATION BY KOBO METHOD

This paper presents the possibility of consolidating side products of turning of aluminum alloys into the form and properties of solids metals using low-temperature KoBo extrusion method has been assessed.The proposed method is based on cold compaction of chips into briquettes, and then extrusion by KoBo method at room temperature. The extruded wires were tested for mechanical properties (uniaxial tensile test and Vickers hardness test), and compared with specific mechanical properties of solid material. A very good effect of chips compaction has been proved by KoBo method, which has been confirmed by relatively slightly different mechanical properties of the material after consolidation compared with the solid one.

The effect of various Co contents on the microstructure and properties of Ti(C,N)-TiB2-Co cermets prepared in situ via reactive hot pressing

Ti(C,N)-TiB2-Co cermets were in situ synthesized, via reactive hot pressing from the Co-Ti-C-BN system, with a Co content ranging from 6 to 22 wt%. The microstructure, relative density, hardness, and fracture toughness of the sintered compacts was investigated by light microscopy, scanning electron microscopy, ceramic densitometry, and Vickers hardness test. The investigations indicate that during hot pressing (compacting pressure = 30 MPa), when the Co content is 14–22 wt%, the metal binder is extruded. Co and Ti are included in the extrudate, breaking the original ratio and deteriorating the properties of the sintered products. As the Co content increases from 6 wt% to 12 wt%, the porosity increases, and the relative density increases from 97.2% to 99.5%. The fracture toughness increases from 6.1 to 6.8 MPa m1/2. The Vickers hardness first increases from 1897 HV10 to the maximum 1960 HV10 and then decreases slightly to 1945 HV10.

Effect of NaOH Concentration on the Microstructure and Mechanical Properties of the PEO Coatings on Mg-Al3-Zn1 Alloy

In this work, the effect of NaOH concentration on the properties of PEO coatings formed on AZ31B Mg alloy is studied. Composition and structure analysis of coatings were carried out by XRD and SEM. From the results, it was found that the number of pores, defects and width of the discharge traces are highly dependent on NaOH concentration. Major phases of the coating identified from XRD were consisted of MgO and Mg2SiO4. The crystallinity of the coatings and magnitude of MgO phase was highly incremented with NaOH concentration. From the Vickers hardness test it was observed that hardness of the coatings prepared in 2g/l of NaOH have the highest values~1050HV, with peak wear resistance values.