فصلنامه علوم و مهندسی سطح ایران
پیاپی 61 (پاییز 1403)

Teeth play a vital role in the chewing and digestion process, and modern restorative dentistry emphasizes minimally invasive techniques. This study explores the impact of atmospheric cold plasma surface modification on enhancing the bond strength of dental adhesives. Dentin samples treated with cold plasma exhibited significant improvements in surface hydrophilicity (average contact angle reduced from 48.2±4.06 to 8.62±2.17 degrees) and microtensile bond strength (rising from 17.04 MPa to 32.26 MPa in specific groups). Advanced techniques, including Scanning Electron Microscopy (SEM), microtensile testing, contact angle measurement, and Fourier Transform Infrared Spectroscopy (FTIR), were utilized to assess physical, chemical, and mechanical surface changes. The results demonstrate that the combination of cold plasma treatment with conventional adhesive application methods significantly enhances the bond strength and performance of dental adhesives. This research highlights innovative strategies to improve the efficacy of restorative materials in dentistry and underscores the potential of cold plasma technology in advancing restorative techniques.

Machining, as one of the key processes in the production of industrial parts, has always been subject to constant change and improvement. One of the main challenges in this field is to achieve a balance between machining speed, dimensional accuracy, and tool life. This research was carried out to optimize the parameters for turning of VCN150 steel with CBN tools to achieve the highest possible cutting speed in traditional lathe machines without reducing dimensional accuracy. To increase the tool life, the effect of two methods of cooling with compressed air and dry cooling on the erosion rate of the tool's cutting edge was investigated. The parameters investigated were cutting speed in the range of 100 to 500 m/min, feed rate in the range of 0.4 to 2 mm/rev, and cutting depth in the range of 0.25 to 0.75 mm. The results showed that although increasing the depth of the cut shortens the machining time, it can lead to the formation of sharp edges and a reduction in surface quality. The lowest machining time was achieved at a cutting speed of 450 m/min, a feed rate of 2 mm/rev, and a depth of cut of 0.75 mm, and under these conditions, the dimensional difference was greater than the nominal value. The smallest dimensional difference was measured at a cutting speed of 100 m/min, a feed rate of 1 mm/rev, and a depth of cut of 0.75 mm, but was associated with a significant increase in machining time. The results showed that the erosion rate on the tool cutting edge is significantly lower with compressed air cooling than with dry cooling.

Considering the application of A860 carbon steel in various industrial parts, pipes and fittings, the study of the use of ultrasonic hammering process in improving the surface and mechanical properties of this steel in various industries including oil and gas, construction, agriculture, etc. has been required and considered. The aim of this paper is to experimentally investigate the ultrasonic hammering process on the surface hardness of A860 steel. The ultrasonic hammering process was carried out under different conditions including static force of 60, 75 and 90 N, feed speed of 40, 100 and 160 mm/min and number of passes of 1, 2 and 3 passes. To conduct practical ultrasonic hammering tests, the necessary equipment was prepared and an experimental setup was set up. In order to select the hammering conditions and analyze the results, the experimental design method of the response surface methodology (RSM) used and the effect of each variable and their interference effect have been discussed. The results obtained show that ultrasonic hammering process by hammering on the surface and plastic deformation of it has caused a decrease in the grain size of the material surface. By reducing the number of passes, the feed rate and the static load in the ultrasonic hammering process, the hardness value has increased. According to the results obtained, a feed speed of less than 75 mm/min with a single pass will result in a hardness of over 420 Vickers.. It was also observed that at low static load, the number of passes has little effect on the hardness. However, to achieve high hardness at larger static loads, ultrasonic hammering should be performed in one pass.

 This work examined the influence of graphene nanosheets on the microstructure, hardness, and corrosion characteristics of CuNi alloy coatings produced by pulse electroplating. The microstructural analysis indicated that the incorporation of graphene nanosheets into the CuNi alloy matrix altered the surface morphology from a nodular structure to one characterized by spherical granules, resulting in an increase in the surface roughness of the composite coating from 33 to 56 nm. Conversely, the presence of graphene resulted in a hardness increase of approximately 20% due to precipitation. Corrosion tests indicated that graphene's presence in the alloy matrix served as a physical barrier, enhancing corrosion resistance by diminishing the active metal surface area. Consequently, it impeded the infiltration of the corrosive liquid, so decreasing the corrosion rate. The corrosion current density for the corrosion composite sample has risen from 1.8×10-6 to 6.6×10-7 A/cm² in comparison to the alloy sample. The inclusion of graphene sheets has increased the corrosion potential, rendering the composite sample more noble. 

 There is a diverse range of data related to tribological properties and features, scattered across various formats such as scientific articles, technical documents, and databases. This data can be utilized to address complex tribological issues, including examining the relationship between the structure and properties of materials on surfaces under friction and wear. Triboinformatics, by merging tribology and informatics, focuses on leveraging knowledge and analytical tools to investigate tribological problems. Machine learning, a subset of artificial intelligence, offers powerful tools for analyzing complex data and uncovering multidimensional relationships between data. This can enhance our understanding of tribological properties and processes. In this article, we first explain the concept of triboinformatics, and then briefly review the primary machine learning algorithms used by researchers to analyze tribological data. Following this, we examine research conducted in the field of triboinformatics. These studies have employed machine learning tools to link factors such as the chemical composition of materials, manufacturing processes, or mechanical properties with tribological properties, particularly wear rate and friction coefficient. The results reported in these studies demonstrate machine learning's capability to predict tribological properties with accuracies of up to approximately 90%. Such accuracies underscore the potential of machine learning in advancing tribology knowledge and addressing complex issues in this field. 

This study was conducted to evaluate the adhesion strength and oxidation behavior of SiC/Mo-Si-B coating applied on graphite substrates. For this purpose, SiC coating was created on graphite substrate using pack cementation method with NH4Cl activator. The secondary layer Mo-Si-B coating was created using atmospheric plasma spraying (APS) with argon protective shower on the samples. Surface morphology and chemical composition of the SiC and Mo-Si-B coatings were inve stigated by Scanning Electron Microscopy (SEM) equipped with an Energy Dispersive Spectroscopy (EDS) system. Surface analysis by X-ray diffraction (XRD) revealed that the structure of SiC was mainly composed of SiC phase. In the case of Mo-Si-B, different phases of Mo and Si, Mo and B, and pure Mo were identified. The adhesion of the multi-layer coating was evaluated by tensile test which indicated a sufficient adhesion and cohesion of the coating. The oxidation test was carried out in the air at 1273 K and the time and weight changes were recorded simultaneously. The results showed that the applied coating significantly improves oxidation resistance of graphite with SiO2 and B2O3 glass layers.