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Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

自蔓延高温合成技术

自蔓延高温合成(self-Propagating High Temperature Synthesis,简称SHS),也称燃烧合成(Combustion Synthesis,简称CS),它是一种利用化学反应自身放热使反应持续进行,最终合成所需材料或制品的新技术。

即外加能源(电热或激光等)触发点火剂燃烧,进而引发反应物料(气相一固相,固相-固相、液和一同相等)自发高速反应、放出热髦,反应由局部以燃烧波的形式自动蔓延整个体系,最后获得新的合成材料的技术。反应物可以是元素粉末相互直接棍合或元素粉末与气体,也可用金属氧化物和还原剂及非金属粉末的混合物反应生成热能维持反应持续进行、反应产物必须是稳定的化合物、.该技术具有产物纯度高、设备简单、能耗低‘生产灵活等优点,缺点是工艺参数控制要求较严。已用此法制备出数百种化合物,像各种金属的氮化物、碳化物、硼化物、硅化物、氧化物、氢化物等。S}-IS技术已发展成SH5制粉技术、SHS烧结技术、5H5致密化技术、5HS熔铸技术、5H5焊接技术、SHS涂层技术等。

任何化学物质的燃烧只要其结果是形成了有实际用途的凝聚态的产品或材料,都可被称为SHS过程。在SHS过程中,参与反应的物质可处于固态、液态或气态,但最终产物一般是固态。

燃烧合成的基本要索:

(1)利用化学反应自身放热,完全或部分不需外部热源;

(2)通过快速自动波燃烧的自维持反应得到所需成分和结构的产物;

(3)通过改变热的释放和传输速度来控制过程的速度、温度、转化率和产物的成分及结构。

SHS技术制备的产品纯度高、能耗低、工艺简单,用SHS技术可以制备非平衡态、非化学计量比和功能梯度材料。

其特点为:

①是一种快速的 合成过程;

②具有节能效果;

③可提高合成材料的纯度;

④产物易形成多孔组织;

⑤燃烧产物的组织具有较大的离散性。

因此,探索各种SHS体系的燃烧合成规律,获得均匀组织也是保障SHS产业化的关键。

SHS粉末合成技术包含的工序类似于粉末冶金制粉。但二者又有区别,其区别主要在合成工序。S

HS粉末合成技术的工艺流程如图所示:

Self-propagating High-temperature Synthetic process
什么是离心铸造

离心铸造是将液体金属注入高速旋转的铸型内,使金属液在离心力的作用下充满铸型和形成铸件的技术和方法。离心力使液体金属在径向能很好地充满铸型并形成铸件的自由表面;不用型芯能获得圆柱形的内孔;有助于液体金属中气体和夹杂物的排除;影响金属的结晶过程,从而改善铸件的机械性能和物理性能。 根据铸型旋转轴线的空间位置,常见的离心铸造可分为卧式离心铸造和立式离心铸造。铸型的旋转轴线处于水平状态或与水平线夹角很小(4°)时的离心铸造称为卧式离心铸造。铸型的旋转轴线处于垂直状态时的离心铸造称为立式离心铸造。铸型旋转轴线与水平线和垂直线都有较大夹角的离心铸造称为倾斜轴离心铸造,但应用很少。

Self-propagating High-temperature Synthetic process
Self-propagating High-temperature Synthetic process

离心铸造最早用于生产铸管,随后这种工艺得到快速发展。国内外在冶金、矿山、交通、排灌机械、航空、国防、汽车等行业中均采用离心铸造工艺,来生产钢、铁及非铁碳合金铸件。其中尤以离心铸铁管、内燃机缸套和轴套等铸件的生产最为普遍。对一些成形刀具和齿轮类铸件,也可以对熔模型壳采用离心力浇注,既能提高铸件的精度,又能提高铸件的机械性能。

离心铸造的优点:

1)几乎不存在浇注系统和冒口系统的金属消耗,提高工艺出品率;

2)生产中空铸件时可不用型芯,故在生产长管形铸件时可大幅度地改善金属充型能力,降低铸件壁厚对长度或直径的比值,简化套筒和管类铸件的生产过程;

3) 铸件致密度高,气孔、夹渣等缺陷少,力学性能高;

4) 便于制造筒、套类复合金属铸件,如钢背铜套、双金属轧辊等;成形铸件时,可借离心力提高金属的充型能力,故可生产薄壁铸件。

离心铸造的缺点:

1)用于生产异形铸件时有一定的局限性。

2)铸件内孔直径不准确,内孔表面比较粗糙,质量较差,加工余量大; 3)铸件易产生比重偏析,因此不适合于合金易产生比重偏析的铸件(如铅青铜),尤其不适合于铸造杂质比重大于金属液的合金。

基本原理 

很多高放热SHS体系的燃烧温度超过燃烧产物的熔点,燃烧后的产物是熔体。这种SHS体  系与常规的冶金方法相结合,产生了SHS技术,利用SHS法得到熔体,用常规冶金法处理熔体[14,15]。SHS冶金包括SHS铸造和SHS-离心技术。铝热反应由于其高放热而被广泛用于SHS冶金。其化学反应式为:    

化学反应式

SHS-离心法

在许多石油化工、电力及冶金行业,钢管的使用寿命成为人们最关心的问题,然而,由于钢管的内径小、长度大,用其它的防腐处理方法很难实现,而用此工艺便可很容易地解决。它是利用铝、镁、硅、锆等粉末与金属氧化物的高放热化学反应,依靠化学反应潜热加热反应物——陶瓷与金属或陶瓷与陶瓷。由于反应温度超过了陶瓷及金属的熔点,整个体系处于熔融状态。在离心力的作用下,熔体按密度大小分层,大密度的组分与钢管基体结合,小密度的陶瓷组分涂覆在钢管的内壁,形成陶瓷涂层。目前,涂层内衬钢管的生产技术已相当成熟。

SHS-离心法

SHS-重力法

比较直的钢管采用离心法是可以的,如果是弯管或其它不规则形状的钢管仍采用离心法显然 是不可行的,经过工程技术研究人员的努力,利用重力原理使得在SHS过程中熔体涂覆到钢管的内壁。因铝热反应产生的高温使反应物处于熔融状态,钢管中在反应物料上形成了由金属Fe及陶瓷两相熔体组成的熔池,由于Fe的密度大于涂层相的密度,在重力作用下,两熔体分离,Fe沉积于熔池的底部,熔融的涂层相浮于熔池的上部。随着自蔓延反应的进行,液面逐渐下降,导致Fe的液相和陶瓷液相依次附与钢管内壁并结晶凝固,从而在钢管内壁形成连续均匀的涂层。

其原理如图所示。

SHS-重力法原理

离心铸造工艺过程:

立式离心铸造机

金属过滤:有些合金液中有较多难于除去的渣滓,可在浇注系统中放各种过滤网清除渣子,如泡沫陶瓷过滤网、玻璃丝过滤网等。

浇注温度:离心铸件大多为管状、套状、环状件,金属液充型时遇到的阻力较小,又有离心压力或离心力加强金属液的充型能力,故离心铸造时的浇注温度可较重力浇注时低5~10°C。

离心铸造双金属耐磨管设备
离心铸造双金属耐磨管设备


 

Properties of the Ceramic-lined Steel Composite Pipes >>
Ceramic (Corundum: a-Al2O3) lined abrasion resistant straight pipe and fittings are lined with highly abrasion resistant ceramic by SHS ----Characteristics of SHS self-burning ceramic composite pipe
Abrasion resistant pipe specification, Standard and identification

Classification and designation
of wear-resistant pipes
for power industry


Pipe elbows be Long-term
use in power plants

Because the outer surface behaves like mild steel, the product can be cut and welded with proper procedure in the field, configured into a variety of fittings, and can accept the standard end options of flanges, weld rings and couplings.

Abrasive Applications

One-hundred-twenty-nine-million tons of coal ash—a byproduct of the coal burning process—is produced every year. Most power plants transport the coal ash in liquid form to large surface impoundments or in solid form at landfills near the facility through long lengths of steel piping, which can range in length from several thousand feet to miles.

Wear-resisting comparative table of ceramic lined pipe
Sand injection test 30% Transfer test of sludge with SiO2
Material Volume diminution
(cm3)
Material Volume diminution
(cm3)
Ceramic lined
Steel pipe
0.0022 Ceramic lined
Steel pipe
3
Ceramic pipe
Al2O397%
0.0025 S45C 25
Application of Abrasion resistant pipe

Abrasion resistant pipe applied in coal-fired power plant ash and slag discharge tube, powder, powder tube, desulfurization pipeline,in addition also widely used in the following industries:

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The warranty is determined to each creator and the maximum duration maximally in service. Should any of the RS fail within the warranty period, We'll replace or repair the defective product (s) at No. end user. Please contact the Sunny steel for details on the How to obtain a warranty for our products.

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As part of our quality regimen, 100% of incoming raw materials, semi-finished products, as well as finished products are thoroughly inspected prior to being entered into our inventory. We have established multiple hold points throughout fabrication as well as a comprehensive final inspection for all products.



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