Search results

This paper investigates the degree of competitiveness within the Turkish cement industry, employing firm-level quarterly data spanning from 2008 to 2016.

To assess the level and trajectory of competition among Turkish cement firms, we employ the Boone indicator (β) as formulated by Boone (2008). This indicator, rooted in the concept of relative profit differences (RPD), serves as a robust metric for gauging competitive dynamics. According to the ß indicator, firms exhibiting higher relative efficiency are expected to secure greater profits and market shares in a fiercely competitive market. Additionally, we utilize concentration indices for the purpose of revealing comparable findings.

Empirical findings reveal that an enhancement in firms' efficiency corresponds to a proportionally modest increase in either market share or profits, implying a lower degree of competition within the Turkish cement industry. Although the specific magnitudes of ß estimates exhibit temporal fluctuations, we may conclude that the Turkish cement industry does not conform to the ideals of perfect competition. The concentration indices calculated on the sample also support this result.

This research is limited to the Turkish cement companies over the period 2008–2016.

The studies measuring the level of competition in the Turkish cement sector are generally based on concentration ratios. In this study, we assess the competition level by using a different methodology based on parametric procedures.

This study aims to investigate the tribological performance of neat polyamide-imide (PAI) and PAI composite (PAI + 12% graphite + 3% polytetrafluoroethylene [PTFE]) under varying mediums and conditions, including dry sliding, distilled water and seawater lubrication, to determine their suitability for high-stress applications.

Tribological tests were conducted using a pin-on-disc setup with AISI 316 L stainless steel (SS) as counterface. Experiments were carried out under loads of 150 and 300 N and sliding speeds of 1.5 and 3.0 m/s. Values of temperatures, friction coefficients and wear rates were recorded to analyze the effect of fillers and lubrication mediums.

The PAI composite outperformed the neat PAI under all conditions, showing significant reductions in friction coefficients and wear rates. Seawater lubrication yielded the best results, achieving friction coefficients of 0.05 and 0.01 and specific wear rates of 18.10⁻¹⁶ m²/N and 1.10 ⁻¹⁵ m²/N, for neat PAI and PAI composite, respectively. Graphite and PTFE fillers enhanced lubrication, reduced surface temperatures and mitigated abrasive and adhesive wear mechanisms. Superior cooling and lubrication effects of the seawater contributed to these improvements.

Previous studies mainly focused on dry sliding and distilled water lubrication for the PAI and its composites, with no research on the seawater conditions. This study compares the tribological behaviors of the neat PAI and PAI composite against AISI 316 L SS under dry sliding, distilled water and seawater lubrication.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0302/