Search

In orbital welding technology, it is difficult and time-consuming to make a standard weld by manual welding. This requires a skilled weld. Therefore, a more optimal welding method than automatic rotary welding has been created to replace the conventional manual welding method. This significantly improves weld quality and reduces welding time. In this explanation, we have experimented with an automatic orbital welding device that integrates a filler wire-feeder device into the welding process. We refer to the American National Standard AWS D18.1/D18.1M: 2009 documents to review the weld results. We then analyze the advantages and disadvantages of the weld and propose solutions.

Polybutylene terephthalate (PBT) has been proven to be a potential material for modern car bumpers. However, the potential of PBT is limited by its low notched impact strength. The main aim of this study is the improvement in the notched impact strength of PBT by blending with polycarbonate (PC). PBT/PC blend at different ratios (95/5, 90/10, 85/15, 80/20) is investigated in notched Izod impact strength (ASTM D256) and hardness (ASTM D2240). Results are compared to those of neat PBT. It was found that notched Izod impact strength decreased with increasing PC rate in the blend, overall, from 4.35 kJ/m2 of neat PBT to 3.37 kJ/m2 of 80/20 blend. The microstructure of testing samples was observed through FESEM images taken at fracture surfaces to determine the cause of the decrease. The low interfacial adhesion between PBT and PC phases is believed to be the main reason. However, an increase in notched impact strength was shown, from 4.18 kJ/m2 of 95/5 blend to 4,71 kJ/m2 of 90/10 blend. This result is presumed to be due to the compatibilizing effect of PBT-PC copolymers formed during the melt blending process. Hardness testing result demonstrates neither significant improvement nor deterioration. It concluded that it is possible to improve the notched impact strength of PBT by blending with PC. The PBT/10% PC blend is a suitable choice for car bumper material since its notch impact strength is higher than neat PBT.

Polybutylene terephthalate (PBT) is a brittle polymer with the disadvantage of low impact toughness, so it is not easy to meet the requirements of both high tensile strength, flexural strength, and high impact strength. In this study, PBT/polycarbonate (PC) blends at different ratios of 95/5, 90/10, 85/15, and 80/20 are investigated. Tensile strength, flexural strength, and unnotched Izod impact strength are studied according to the ASTM D638, ASTM D790, and ASTM D256 standards. The results show that tensile strength, which increased with increasing PC content, is 53.00, 62.34, 60.59, 62.98, and 64.46 MPa for 0, 5, 10, 15, and 20% PC samples. Flexural strength and elastic flexural testing of PBT/PC blends are higher than neat PBT. In addition, the unnotched Izod impact strength of PBT/PC is also higher than PBT. However, when PC content increases, impact strength tends to decrease. Impact strength is 44.82, 80.46, 68.82, 50.45, and 48.05 kJ/m2 corresponds to 0, 5, 10, 15, and 20% PC, in which 5% PC sample is twice as high as the impact strength of PBT. Microstructure of the blends has shown that PC has become dispersed phase in PBT matrix. The size and quantity of dispersed PC particles increase with increasing PC rate in the blend. Thus, when adding PC, PBT/PC all meet the requirements of high tensile strength, flexural strength, and high impact strength. The PBT/5% PC model gives the highest impact strength while still ensuring durability, which potential application for making car door handles.

This study aimed to investigate EFL students’ perceptions of an English language training curriculum for English language majors at a university in Vietnam. The participants included one hundred attendants of the English language courses in the curriculum. The data were collected through questionnaires and semi-structured interviews. The study results reveal that five components of the English language training curriculum for English language majors at the university (including objective, content, material, teaching method, and assessment) have not yet been done at optimum, as perceived by the students. The participants also suggest making certain modifications in the five components of the curriculum to make it more effective and better adjusted to the learners’ needs. Several important implications and recommendations relevant to the field have also been included.

Applying the Laser Cladding method to create composites cladding Co+(10; 20; 30) % TiC on the surface of Hot Die, SKD61 steel. Using Micro-hardness tester and Microscope (SEM) to measure the hardness and analyze the distribution of TiC particles in the clad. The results indicated that the average hardness of the TiC/Co-based composites cladding cross-section Co-based+10% TiC, Co-based+20% TiC, Co-based+30% TiC in order is 589 HV0.2, 788 HV0.2, and 934 HV0.2. All of these claddings have the hardness higher than SKD61 steel in order is 2.6, 3.5, and 4.2 times. From that show that, the hardness of the claddings has a close relationship with percentage of TiC particles. Besides, the regression models exactly show that the hardness of the claddings is: y1 =23.8438-7.3494x, y2=9.7389x+44.6927, y3=13.6597x+35.511 by 10, 20, 30% wt TiC particles in the claddings, which create the scientific theory to apply from some other carbides to reinforced for the cladding.