Asbestos was added as an common ingredient to Brake Pads post-WWI, as car speeds began to increase, because research showed that its properties allowed it to absorb the heat (which can reach 500 °F) while still providing the friction necessary to stop a vehicle. However, as the serious health-related hazards of asbestos eventually started to become apparent, other materials had to be found. Asbestos brake pads have largely been replaced by non-asbestos organic (NAO) materials in first world countries. Today, brake pad materials are classified into one of four principal categories, as follows:
Non-metallic materials - these are made from a combination of various synthetic substances bonded into a composite, principally in the form of cellulose, aramid, PAN, and sintered glass. They are gentle on rotors, but produce a fair amount of dust, thus having a short service life.
Semi-metallic materials - synthetics mixed with varying proportions of flaked metals. These are harder than non-metallic pads, more fade-resistant and longer lasting, but at the cost of increased wear to the rotor/drum which then must be replaced sooner. They also require more actuating force than non-metallic pads in order to generate braking torque.
Fully metallic materials - these pads are used only in racing vehicles, and are composed of sintered steel without any synthetic additives. They are very long-lasting, but require more force to slow a vehicle while wearing off the rotors faster. They also tend to be very loud.
Ceramic materials - Composed of clay and porcelain bonded to copper flakes and filaments, these are a good compromise between the durability of the metal pads, grip and fade resistance of the synthetic variety. Their principal drawback, however, is that unlike the previous three types, despite the presence of the copper (which has a high thermal conductivity), ceramic pads generally do not dissipate heat well, which can eventually cause the pads or other components of the braking system to warp.However, because the ceramic materials causes the braking sound to be elevated beyond that of human hearing, they are exceptionally quiet.
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Decentralized industrial layout, leading role of leading enterprises is not strong, product grade is not high, innovation ability is not strong, and enterprise operation difficulties are aggravated... Since the rapid development and development of Zhoushan shipbuilding industry in the early 21st century, there are still some prominent and deep contradictions. And the problems, especially after the international financial crisis, the global ship market and the industrial structure have undergone tremendous changes, which has made the shipbuilding enterprises more and more difficult. The "Three-Year Action Plan for the Construction of the New Area of ​​Zhoushan Islands in Zhejiang Province" proposes that in the next three years, Zhoushan City will comprehensively promote the construction of a new national industrialization demonstration base for ships and marine engineering equipment, integrate and upgrade the shipbuilding industry, develop and manufacture high-tech green ships, and actively develop ship-to-ship The industry will moderately develop the green ship dismantling industry and improve the design level of the shipbuilding industry. Strive to reach the total output value of the shipbuilding industry in Zhoushan by 100 billion yuan in 2015, of which the output value of marine engineering has reached more than 20 billion yuan. "Currently, Zhoushan Shipbuilding Industry is a key period for maintaining stability, adjusting structure and promoting transformation." Mao Runzhou, director of the Comprehensive Department of the Municipal Economic and Information Committee, believes that the transformation and upgrading of Zhoushan's modern marine industry is not to abandon all, but to be down-to-earth in itself. On the basis of transformation and upgrading, such as the shipbuilding industry, on the one hand, it can self-improve and build high value-added ships. On the other hand, it can also develop into marine engineering and develop into ship electronics and ship design.
Mao Runzhou said that the city will soon introduce an implementation plan for the "National New Industrialization Industry Demonstration Base for Ships and Offshore Equipment." In the coming period, Zhoushan Shipbuilding Industry will adhere to the principle of “resource intensification, industrial agglomeration and dislocation development†in accordance with the requirements of building a national new industrialized industrial demonstration base, promote the further agglomeration of the shipbuilding industry, and gradually form a ship and offshore agglomeration area in the northern part of the island. Block, six horizontal northern ship and offshore assembly block, Laoshan ship and offshore assembly block three core agglomeration blocks.
In the vigorous development of marine engineering equipment manufacturing industry, Zhoushan City will rely on the existing foundation to build a marine engineering equipment repair base and cultivate international leading marine engineering equipment manufacturing industry, such as accelerating Wison Heavy Industries, Pacific Offshore Phase II and Liuheng. Construction of a number of marine engineering projects such as COSCO, Changhong International and Jinhai Heavy Industry, and vigorously develop equipment products such as deep water exploration, deep water production, ocean emergency rescue, and deep water remote recharge. Strengthen cooperation with related enterprises at home and abroad, introduce international advanced technology, and focus on the development of jack-up drilling platforms, deep-water semi-submersible platforms, floating production and storage devices, and key systems and supporting equipment for offshore engineering equipment to increase localization rate and promote power. And supporting equipment technology leapfrog development.
In the integration and upgrading of the shipbuilding industry, R&D and manufacturing of high-tech green ships will focus on high-tech and high value-added ships such as large container ships, large LPG carriers, LNG carriers, luxury cruise ships, yachts, ocean fishing vessels and special vessels; Develop the shipbuilding industry, moderately develop the green ship dismantling industry, and improve the ship design level.