Table 2.
Overall result of individual studies
| Study and publication | Surface characteristics | Friction | Surface hardness | Load deflection | Elastic modulus |
|---|---|---|---|---|---|
| Redlich et al. (2008)[13] | X-ray diffraction and SEM shows Poor crystallinity. Adhesion-remains unaffected after bending |
Decreased friction coefficient by 50% -coated group Increased friction coefficient in uncoated group |
---- | ---- | ---- |
| Somorodnitzky et al. (2009)[14] | Well-defined continuous coating Bending test-undamaged coating without cracks after bending test |
Reduction of 20 to 30% of static and kinetic friction in coated and increased static and kinetic friction in uncoated group. | ---- | ---- | ---- |
| Muguruma et al. (2011)[15] | Surface roughness not affected by coating | Significantly reduced friction in coated NiTi and S. S group compared with control. | ---- | ---- | 1944 GPa 74.9 GPa 277.4 GPa 82.9 GPa |
| Krishnan et al. (2012)[16] | The Coating as well its varied thickness from each group of specimens was clearly visible and minor drawing line was visible after sliding. | Group 1-more friction Group 2-less friction compared to group 1 Group 3-less friction group 1and group 2 |
---- | Group 2 and 3 showed low defection rate compared to Group 1 | ---- |
| Kang et al. (2015)[17] | Slight decrease in roughness which was statistically insignificant | WCON-BCON and WDLC-BDLC=lowest frictional coefficient. WDLC-BCON and WDLC-BDLC=high frictional coefficient. |
Extensive wear and plastic deformation in WCON-BCON and WCON-BDLC | ---- | ---- |
| Zhang et al. (2016)[18] | SEM Shows- 1 µm of coating thickness and ultra fine crystal grains. Nitrocarborized-relatively smooth compared to control. |
Nitrocarborized- significantly decreased by 22% than control group DLC-friction decreased compared to control group |
DLC-685.17HV
Nitro-119.58 HV Control 468.4HV |
---- | DLC-74.17 Gpa Nitro-206.03 Gpa Control-204.2Gpa |
| Behroozian et al. (2016)[19] | Uniform distribution of nano particles | ZZ- maximum frictional force OZ-minimum frictional force ZO- no significant difference OO-no significant difference |
---- | ---- | ---- |
| Shah et al. (2018)[20] | ---- | Group 3 shows significant reduction in friction and others showed no significant reduction in friction | ---- | ---- | ---- |
| Gracco et al. (2019)[21] | Homogenous well-defined continuous coatings with spherical and cylindrical structures. | Group 3 and 4 shows lower friction values when compared with other group. But there is no significant difference between group 3 and group 4. | ---- | ---- | ---- |
WCON-BCON (conventional S. S wire and bracket), WCON-BDLC (conventional S. S wire and DLC coated bracket), WDLC-BCON (DLC coated S. S wire and conventional bracket), WDLC-BDLC (DLC coated S. S wire and bracket), OO- uncoated S. S wire and uncoated bracket, ZO- coated S. S wire and uncoated bracket, OZ- uncoated S. S wire and coated bracket, ZZ- coated S. S wire and coated bracket