B-18 EFFECT OF SURFACE ROUGHNESS, POWDER SIZE AND PRESSURE ON SUPERPLASTIC BORONIZING OF DUPLEX STAINLESS STEEL(Session: Surface Modification)

Author(s):  
Yusof H.A.M ◽  
Jauhari I ◽  
Rozali S ◽  
Hiroyuki O
2010 ◽  
Vol 297-301 ◽  
pp. 227-232 ◽  
Author(s):  
Sharidah Azuar Abdul Azis ◽  
Iswadi Jauhari ◽  
Nik Rozlin Nik Masdek ◽  
Nor Wahida Ahamad ◽  
Hiroyuki Ogiyama

Superplastic carburizing (SPC) is a carburizing process that combines carburizing with superplastic deformation. Since SPC involves direct interaction between the superplastically deformed surface and the solid carbon medium, the effect of surface roughness on the process cannot be disregarded. This paper presents the study of surface roughness and initial pressure effects on superplastic carburizing of duplex stainless steel (DSS). SPC was conducted under four different surface roughness (Ra) conditions of 0.9, 0.3, 0.1 and 0.03 μm. The microstructure, surface hardness, and carburized layer thickness were studied. Comparisons were also done on non-superplastic material which has a coarse microstructure. The results showed that the surface roughness strongly affected the properties of the superplastically carburized duplex stainless steel while its effects on the non-superplastic material were not that obvious.


Author(s):  
Y. Arsyad ◽  
R. Linggam ◽  
MOINUDDIN MOHAMMED QUAZI ◽  
M.H. Aiman ◽  
M. Ishak ◽  
...  

Laser surface modification is an emerging process that can produce texture on a work surface and effectively enhance surface topography while altering surface roughness. Laser surface modification is a sensitive process that depends on various laser processing parameters such as power, scanning speed, hatching distance. The significance of this work is to examine the influence of hatching distance on the surface characteristic of 2205 duplex stainless steel samples. The surface transformation and variation of the surface roughness properties of the materials were examined. The hatching distance was varied from 0.1 to 0.005 mm. Results indicate that, as the hatch spacing decreases, the overlap of laser track increases, thereby resulting in a decrease of surface roughness. Meanwhile, with the increase of hatch distance, the clear overlay tracks were transformed to irregular wavy surface. The best hatch distance parameter obtained was 100 μm that resulted in the highest roughness of 8.45 μm. Experimental results illustrate that, when the optimum hatch distance of 100 μm was adopted, the polished smooth surface of 2205 duplex stainless steel with initial average roughness value of 0.19 μm increased by 42 times of the polished surface roughness. A strong correlation between hatching distance and roughness was established in 2205 duplex stainless steel. High depth of the altered surface topography and increased roughness were linked to higher levels of hatching distance.


Author(s):  
Vimal Munot ◽  
Ramesh P Nayakar ◽  
Raghunath Patil

Introduction: In two-stage implants, micro-gap between the fixture and the abutment and the superstructure are the potential areas to cause peri-implantitis. The surface roughness and surface energy of the implant abutment materials play an important role in the microbial colonisation on their surface and can help the clinician to choose a better implant abutment material in terms of microbial affinity. Aim: To evaluate the effect of surface characteristics of different implant abutment materials on microbial adhesion. Materials and Methods: The comprehensive analytical experimental study was conducted at KAHER KLE VK Institute of Dental Sciences, Belagavi between Jan 2017- Dec 2017. Forty-five (n=45) identical disc shaped specimens were fabricated using; Zirconia (Group A), Titanium alloy (Group B) and Surgical Grade Stainless Steel (Group C). The surface roughness was assessed for all test groups by Profilometer and Scanning Electron Microscope (SEM). The Surface energy was evaluated for all the test group specimens using Goniometer. Microbial adhesion and assessment were performed using sonicating and vortexing method for all the three groups using three different bacterial strains. The Colony Forming Units for all the specimens were tabulated and subjected to statistical analysis to draw the conclusions from the resultant data.The resultant data was analysed using SPSS software (Version 20). In order to collectively compare the means of the study groups pair-wise comparison of the test group was done using paired t-test with (p<0.05), and correlation between the surface parameters and CFU counts was done using Karl Pearson’s correlation coefficient. Results: On pair-wise comparison of three Groups (A, B, and C) with respect to surface roughness, there were statistically significant differences in surface roughness Ra values between all the groups p<0.001. On pair-wise comparison of all the three Groups with respect to surface energy, there were statistically significant differences in Wetting Angle (WA) values between all the groups (p<0.001**) except between group B and A (p=0.15). Zirconia showed the least CFU counts for Pi and Aa though the differences were not statistically significant. Karl Pearson’s correlation coefficient between surface roughness and surface energy with CFU counts showed a strongly positive correlation for all microbial species and were statistically significant p<0.001**. Conclusion: There was a strongly positive correlation of surface roughness and surface energy to CFU counts. Zirconia showed a low colonisation potential against P.intermedia and A.actinomycetemcomitans than titanium alloy and surgical grade stainless steel.


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