Application of the Technique For Order Preference By Similarity To Ideal Solution Method in Determining Contract Employees to Become Permanent Employees

Refratech Mandala Perkasa (RMP) is a refractory cement manufacturing company. The company also operates in the manufacture of refractory cement made for repair of hot coatings, boilers, rotary kilns, incinerators, ovens and chemicals for steel metals, as well as ferrous & non ferrous foundries. In this company there are contract employees and permanent employees, contract employees are employees or workers whose working period is limited by a certain time according to the agreement within the company. While permanent employees are workers whose working period is approximately until they receive certain benefits according to the work agreement. This research was conducted to assist companies in decision support using the Topsis method in determining the appointment of contract employees to permanent employees based on predetermined criteria, namely Knowledge and Skills at work, Quantity and Quality of Work, Job Responsibilities, Initiatives in Work, and Compliance. on rules or discipline. The results of this study indicate that the determination of the ranking of prospective permanent employees can be obtained from the calculation results of the TOPSIS method, where the results of prospective employees are based on predetermined administrative criteria. Prospective permanent employees who have the highest rank have the right to be selected first. The accuracy of the implementation of the TOPSIS method on the system plays a major role in the effectiveness and efficiency of the company's services to consumers compared to before the system was implemented. With the implementation of this DSS system, it can help companies to make it easier to make decisions to survey prospective permanent employees and optimize employee performance.

Pengaruh Waktu Pencampuran terhadap Kekerasan Vickers Material Crucible Berbahan Limbah Evaporation Boats, Kaolin dan Semen Tahan Api

Evaporation boat waste contains Boron Nitride (BN) and Titanium Diboride (TiB2) so that it has electrically conductive properties with high resistance to chemicals and heat. In addition, the combination of these materials has high thermal conductivity properties with a melting point of up to 2700oC and has an oxidation resistance of up to 1000oC so it is very suitable if applied to crucibles, or refractory. The purpose of this study was to determine the effect of mixing duration on the hardness of the crucible material made from a mixture of evaporation boats waste, kaolin and fire mortar SK-34. The mixing process of evaporation boats waste, kaolin and refractory cement is carried out using a mixer machine with a duration of 30, 60 and 90 minutes. The compaction process was carried out on the mixture with a force of 40 kg/cm2 to produce a cylindrical test specimen. After seven days, the specimens were sintered at 1000oC for 2 hours. The hardness test process was carried out with the FM-800 microhardness tester machine to determine the effect of mixing duration on the final product hardness. The highest hardness of 37,2 HV was found in the final product with a mixing duration of 90 minutes. The hardness of final product is increasing with an increase in mixing duration.

Influence of substitution of Portland cement CP-II-Z32 by refractory cement on residual properties of high-temperature concrete

Concrete structures must be sized to ensure stability over their lifetime. Moreover, there are criteria that must be followed for fire safety verification. Given this context, this study aimed to evaluate the influence of the partial and integral replacement of CPII-Z32 cement by a refractory cement in concrete compositions related to the residual properties after exposure to different temperature levels. For the tests, cylindrical specimens were molded with cement replacement percentages of 0% (reference), 50%, and 100%, and exposed at 450 °C and 900 °C without load. The results showed a change in the color of the specimens and a reduction of the mechanical strength with increasing temperature. The increase in the percentage of refractory cement resulted in lower heat conduction for the concrete made with this material.

APPLICABILITY OF CARBON FIBRES IN REFRACTORY CEMENT COMPOSITES

The main objective of this article is to present the influence of high temperatures on mechanical properties of advanced refractory cement composite reinforced with carbon fibres. The presented material is suitable for industrial applications and can withstand elevated temperatures up to 1000 °C. The action of high temperatures was investigated on two temperature levels 600 °C and 1000 °C and was compared to reference specimens dried at 105 °C. The carbon fibres with flexural strength of 4100MPa were applied in dosage 0.50 %, 0.75% and 1.00% of the total volume. The second investigated modification was mutual ratio between aluminous cement and fine ceramic powder. The influence of high temperatures was investigated by measuring the bulk density, compressive and flexural strength, dynamic modulus of elasticity and fracture energy; all measured on prismatic specimens 40 × 40 × 160 mm. The workability of fresh mixture was limited by the maximum dosage of carbon fibres in 1% of the total volume. Based on the workability and evaluation of residual mechanical properties after temperature loading, the best was found to be the combination of carbon fibres in dosage of 0.75% by volume.

Influence of Mineral Admixtures on Fracture Energy of Refractory Cement at Elevated Temperatures

The influence of three mineral admixtures, Silica Fume (SF), Fly Ash (FA), and Rice Husk Ash (RHA) on the fracture energy of Refractory Cement (RC) over a wide range of temperature from 300K to 1173K is studied. The optimum percentage replacement of RC by these admixtures is found to be around 0.5 for all the temperatures considered but for FA. Fracture energy of control (0% admixture) and blended RC (with 0.5% admixture) are determined by three point bending of notched beam specimens. Fracture energy of RC blended with the three mineral admixtures is lower than that of control RC for temperature range of 300K to 873K. But at elevated temperature of 1173K, blending plays its role as an admixture. Experimental results are corroborating with XRD. It is observed that phenomenon of pseudo dryness of Gismondine in the blended RC causes higher fracture energy which is double that of RC only at 1173K.

Resistance of Refractory Cement Composite to Cyclic Temperature Loading

The aim of this study was to describe mechanical properties decline and macroscopic changes after cyclic thermal load of refractory slabs. Investigated elements were made from refractory cement composite containing natural basalt aggregate, fine ceramic powder, aluminous cement with high volume of Al2O3, different dosage of basalt fibres, water and plasticizer. Slabs with dimension 300 x 200 x 38 mm were exposed to elevated temperature 600 °C for three hours (temperature gradient 10 °C/min) and cooled to laboratory condition. This loading cycle was repeated six times. Tensile characteristics were investigated by bending test with clear span of supports 200 mm. Maximum force and displacement increased with increasing amount of basalt fibres. Maximum flexural strength of slabs corresponded to material characteristics measured on specimens 40 x 40 x 160 mm. Slabs with 1% of basalt fibres achieved flexural strength 4.8 MPa (after six loading cycles). The highest weight decline took place after the first loading cycle. Successful design of original fibre-cement composite has been approved by cyclic loading of larger dimension specimens.